Final Report
Ultra-Low NOx Near-Zero Natural Gas Vehicle
Evaluation ISX12N 400
April 2018
Submitted by:
Author: Dr. Kent Johnson (PI), Dr. George K (Co-PI)
PhD. Candidate Cavan
College of Engineering-Center for Environmental Research and Technology
University of California
Riverside, CA 92521
(951) 781-5791
(951) 781-5790 fax
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Disclaimer
This report was prepared as a result of work sponsored in part by the California Energy
Commission (Commission), the South Coast Air Quality Management District (SCAQMD),
Southern California Gas Company (SoCalGas) and Clean Energy. It does not necessarily represent
the views of the Commission, SCAQMD, SoCal Gas or Clean Energy, their employees, or the
State of California. The Commission, SCAQMD, SoCalGas, Clean Energy, the State of California,
their employees, contractors, and subcontractors make no warranty, express or implied, and
assume no legal liability for the information in this report; nor does any party represent that the
use of this information will not infringe upon privately owned rights. This report has not been
approved or disapproved by the Commission nor has the Commission passed upon the accuracy
or adequacy of the information in this report.
The statements and conclusions in this report are those of the author and not necessarily those of
Cummins Westport, Inc. The mention of commercial products, their source, or their use in
connection with material reported herein is not to be construed as actual or implied endorsement
of such products.
Inquiries related to this final report should be directed to Kent Johnson (951) 781 5786,
Acknowledgments
The work reported herein was performed for Cummins Westport, Inc., as part of SCAQMD
Contract No. 16205 with Cummins Westport, Inc.
The authors acknowledge Mr. Don Pacocha, Mr. Mark Villa, and Mr. Daniel Gomez of CE-CERT
for performing the tests and preparing the equipment for testing and Ms. Grace Johnson for her
analytical support for the particulate matter laboratory measurements.
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Table of Contents
List of Tables ................................................................................................................................. v List of Figures ................................................................................................................................ v Abstract ......................................................................................................................................... vi Acronyms and Abbreviations .................................................................................................... vii
Executive Summary ................................................................................................................... viii 1 Background ......................................................................................................................... 11
1.1 Introduction ....................................................................................................................... 11 1.2 NOx Emissions .................................................................................................................. 11 1.3 Fuel economy .................................................................................................................... 12 1.4 Objectives ......................................................................................................................... 13
2 Approach ............................................................................................................................. 14 2.1 Test article ......................................................................................................................... 14
2.1.1 Engine ....................................................................................................................... 14 2.1.2 Test Fuel.................................................................................................................... 14
2.1.3 Vehicle inspection ..................................................................................................... 15 2.1.4 Test cycles ................................................................................................................. 15
2.1.5 Work calculation ....................................................................................................... 15 2.2 Laboratory ......................................................................................................................... 18
2.2.1 Chassis dynamometer ............................................................................................... 18
2.2.1.1 Test weight ...................................................................................................... 18 2.2.1.2 Coast down...................................................................................................... 18
2.2.2 Emissions measurements .......................................................................................... 18
2.2.3 Low NOx Measurements .......................................................................................... 19
2.2.3.1 Traditional method .......................................................................................... 20 2.2.3.2 Method upgrades ............................................................................................. 20
2.2.3.3 Calculation upgrades ....................................................................................... 21 2.2.3.4 Method evaluation .......................................................................................... 21
2.2.4 NH3, PN, PSD, and BC Measurements..................................................................... 24
3 Results .................................................................................................................................. 25 3.1 Gaseous emissions ............................................................................................................ 25
3.1.1 NOx emissions .......................................................................................................... 25 3.1.2 Other gaseous emissions ........................................................................................... 26
3.2 PM emissions .................................................................................................................... 29 3.3 PN emissions ..................................................................................................................... 31
3.4 Ultrafines........................................................................................................................... 33 3.5 Greenhouse gases .............................................................................................................. 34 3.6 Fuel economy .................................................................................................................... 36
4 Discussion............................................................................................................................. 38 4.1 Transient emissions ........................................................................................................... 38 4.2 Cold start emissions .......................................................................................................... 38
5 Summary and Conclusions ................................................................................................ 40 References .................................................................................................................................... 42 Appendix A. Test Log ................................................................................................................ 44
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Appendix B. Test Cycle Description .......................................................................................... 45
Appendix C. UCR Mobile Emission Laboratory ....................................................................... 50 Appendix D. Heavy-Duty Chassis Dynamometer Laboratory ................................................... 52
Appendix E. Additional Test Data and Results ......................................................................... 55 Appendix F. Engine certification family, details, and ratings ................................................... 60 Appendix G. Coastdown methods .............................................................................................. 61
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List of Tables
Table 2-1 Summary of selected main engine specifications ......................................................... 14 Table 2-2 Fuel properties for the local NG test fuels utilized....................................................... 14 Table 2-3 Summary of statistics for the test cycles performed ..................................................... 15 Table 2-4 NOx measurement methods traditional and upgraded .................................................. 20
Table 2-5 NOx measurement methods traditional and upgraded .................................................. 21 Table 2-6 NOx measurement methods t and f test (paired, two tailed) statistics .......................... 24 Table 3-1 PN Emissions from the ISX12N engine for various cycles ......................................... 32 Table 3-2 Global warming potential for the ISX12N truck tested (g/bhp-hr) .............................. 35
List of Figures
Figure 1-1 Engine dynamometer NOx and PM certification emissions standards (source CWI) . 11 Figure 1-2 In-use emissions from a heavy duty truck tested on UCR’s chassis dyno .................. 12 Figure 1-3 NOx emissions versus fuel consumption tradeoffs during certification testing ......... 12
Figure 2-1 Published ISX12N Natural Gas engine torque curve .................................................. 16 Figure 2-2 Power from the various tests with 1 stdev error bars .................................................. 17
Figure 2-3 Work from the various tests with 1 stdev error bars ................................................... 17 Figure 2-4 Major Systems within UCR’s Mobile Emission Lab (MEL) ...................................... 19 Figure 2-5 Real time raw (CLD and QCL) accumulation NOx with NH3 concentration ............ 22
Figure 2-6 Real time raw (CLD and QCL) and dilute CLD NOx measurements ......................... 23 Figure 2-7 Measured NOx emission for the hot and cold start test cycles ................................... 23
Figure 2-8 Measured NOx emission for the hot start only test cycles .......................................... 24
Figure 3-1 Measured NOx emission for the hot and cold start test cycles ................................... 26
Figure 3-2 Hydrocarbon emission factors (g/bhp-hr) ................................................................... 27 Figure 3-3 CO emission factors (g/bhp-hr) ................................................................................... 28
Figure 3-4 Ammonia emission factors (g/bhp-hr) ........................................................................ 28 Figure 3-5 Ammonia measured tail pipe concentration (ppm) ..................................................... 29 Figure 3-6 PM emission factors (g/bhp-hr) .................................................................................. 30 Figure 3-7 PM emission measurements filter weights and eBC concentration ............................ 30
Figure 3-8 Particle number emissions solid and total (#/mi) ........................................................ 31 Figure 3-9 Particle number emissions solid and total (#/cc)......................................................... 32 Figure 3-10 Percent solid particle number from CPC data (%) .................................................... 33 Figure 3-11 EEPS comparisons for PN (#/mi) ............................................................................. 33 Figure 3-12 EEPS ultrafine PSD CVS measurements for each of the test cycles ........................ 34
Figure 3-13 QCL N20 Results during a cold start ......................................................................... 36 Figure 3-14 QCL N20 Results during a hot start (N20 Multiplied by 100) ................................... 36
Figure 3-15 CO2 emission factors (g/bhp-hr) ............................................................................... 37 Figure 4-1 Accumulated NOx emissions (g) hot start UDDS cycles ........................................... 38 Figure 4-2 Accumulated NOx emissions (g) cold start UDDS cycles.......................................... 39
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Abstract
Heavy-duty on-road vehicles represent one of the largest sources of NOx emissions and fuel
consumption in North America. Heavy-duty vehicles are predominantly diesels, with a recent
interest in natural gas (NG) systems. As emissions and greenhouse gas regulations continue to
tighten new opportunities for advanced fleet, specific heavy-duty vehicles are becoming available
with improved fuel economy. NOx emissions have dropped 90% for heavy-duty vehicles with the
recent 2010 certification limit. Additional NOx reductions of another 90% are desired for the South
Coast Air basin to meet its 2023 NOx inventory requirements.
Although the 2010 certification standards were designed to reduce NOx emissions, the in-use NOx
emissions are actually much higher than certification standards. The main reason is a result of the
poor performance of aftertreatment systems for diesel vehicles during low duty cycle operation.
Recent studies by UCR suggest 99% of the operation within 10 miles of the ports is represented
by up to 1 g/bhp-hr. Thus, a real NOx success will not only be providing a solution that is
independent of duty cycle, but one that also reduces the emissions an additional 90% from the
current 2010 standard.
The ISX12N 400 NG engine met and exceeded the target NOx emissions of 0.02 g/bhp-hr and
maintained those emissions during in-use duty cycles found in the South Coast Air Basin. The
other gaseous and particulate matter were below the standards and/or similar to previous levels.
Particle number, ammonia emissions, and methane emissions were higher than current 2010
certified diesel engines on similar drive cycles. These higher emissions should be considered for
health and environmental impact studies. In general, it is expected NG vehicles could play a
significant role in achieving the NOx inventory goals given the near zero emission factors
demonstrated.
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Acronyms and Abbreviations
ARB ...................................................Air Resources Board
bs ........................................................brake specific
CE-CERT ...........................................College of Engineering-Center for Environmental Research
and Technology (University of California, Riverside)
CFR ....................................................Code of Federal Regulations
CH4 .....................................................methane
CLD....................................................chemiluminescent detection
CO ......................................................carbon monoxide
CO2 .....................................................carbon dioxide
CNG ...................................................compressed natural gas
CPC ....................................................condensation particle counter
CPC_CS .............................................CPC with a catalytic stripper
CWI ....................................................Cummins Westport Inc.
FE .......................................................Fuel economy
FID .....................................................flame ionization detector
GDE ...................................................gallons diesel equivalent
g/bhp-hr ..............................................grams per brake horsepower hour
lpm .....................................................liters per minute
LNG ...................................................liquid natural gas
MEL ...................................................mobile emission laboratory
NG ......................................................natural gas
NOx ....................................................nitrogen oxides
N2O ....................................................nitrous oxides
NH3 ....................................................ammonia
NMHC................................................non methane hydrocarbons
NZ ......................................................near zero
OEM ...................................................original equipment manufacturer
PM ......................................................particulate matter
PM2.5 ..................................................ultra-fine particulate matter less than 2.5 µm (certification
gravimetric reference method)
PN ......................................................particle number
PSD ....................................................particle size distribution
QCL....................................................quantum cascade laser
RPM ...................................................revolutions per minute
scfm ....................................................standard cubic feet per minute
THC....................................................total hydrocarbons
UCR ...................................................University of California at Riverside
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Executive Summary
Heavy-duty on-road vehicles represent one of the largest sources of NOx emissions and fuel
consumption in North America. Heavy-duty vehicles are predominantly diesels, with the recent
penetration of natural gas (NG) engines in refuse collection, transit, and local delivery where
vehicles are centrally garaged and fueled. As emissions and greenhouse gas regulations continue
to tighten, new opportunities to use advanced fleet specific heavy-duty vehicles with improved
fuel economy are becoming available. NOx emissions have dropped 90% for heavy-duty vehicles
with the recent 2010 certification limit. Additional NOx reductions of another 90% are desired for
the South Coast Air basin to meet its 2023 NOx inventory requirements.
Although the 2010 certification standards were designed to reduce NOx emissions, their in-use
NOx emissions are actually much higher than certification standards. The main reason is a result
of the poor performance of aftertreatment systems for diesel vehicles during low duty cycle
operation. Recent studies by UCR suggest 99% of the operation within 10 miles of the ports are
up to 1 g/bhp-hr NOx. Stoichiometric natural gas engines with three-way catalysts tend to have
better low duty cycle NOx emissions than diesel engines with SCR aftertreatment systems. Thus,
a real NOx success will not only be providing a solution that is independent of duty cycle, but one
that also reduces the emissions an additional 90% from the current 2010 standard.
Goals: The goals of this project was to evaluate Cummins West Ports (CWI) ISX12N (Near-zero)
11.9 liter ultra-low NOx natural gas (NG) truck. The evaluation included regulated and non-
regulated emissions, ultrafines, global warming potential, and fuel economy during in-use testing.
This report presents a summary of the results and conclusions for the CWI ultra-low NOx NG
11.9L truck (ISX12N).
Approach: The testing was performed on UC Riverside’s chassis dynamometer with their Mobile
Emissions Laboratory (MEL) located in Riverside CA just east of the South Coast Air Quality
Management District (AQMD). The cycles selected for this study are representative of operation
in the South Coast Air Basin and included drayage port cycles (near dock, local, and regional), the
urban dynamometer driving schedule, and three cycles designed by CARB (called HHDDT cycles).
Measuring NOx at 90% of the 2010 certification level (~ 0.02 g/bhp-hr is approaching the detection
limit of the dilute CVS method. Previously, advanced NOx measurement methods were evaluated
by UCR and the raw measurement method was recommended and utilized (Johnson et al 2016).
The raw NOx chemiluminescence measurement method was also used for this study with the
addition of a new spectroscopy method not susceptible to interferences from NH3 emissions. In
addition to the regulated emissions, the laboratory was equipped to measure particle size
distribution, particle number (both solid and total), equivalent black carbon, ammonia, and nitrous
oxide emissions. The measurements were collected to investigate the benefit of the ISX12N engine
and aftertreatment system compared to other approaches.
Results: The ISX12N NG engine showed NOx emissions below the CARB optional low NOx
standard (0.02 g/bhp-hr) and averaged between 0.0012 and 0.02 g/bhp-hr for the various hot start
tests, see Figure ES-1. The NOx emissions were well controlled at low loads (Creep and Near Dock
cycles) as well as during cruise conditions (Regional and HHDDT Cruise) where diesel vehicles
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tend to have much higher emissions at light loads but perform well at cruise conditions. This
suggests stoichiometric NG engines are a good choice for regional NOx mitigation strategies where
light loads are common.
The NOx emissions reported are the result of emission spikes during de-accelerations from
consistent points with-in the test cycle, see Figure ES-2. More than 90% of the NOx emissions
resulted from these transient de-accelerations. The variability in the emissions is a result of the
magnitude of the NOx spike. This suggests possible driver behavior may impact the overall NOx
in-use performance of the vehicle where more gradual de-accelerations are desired, such as with
hybrid applications.
Figure ES-1 Cycle averaged NOx emissions for the ISX12N 400 equipped truck
Cold start NOx emissions represent a significant part of the total NOx emissions reported. The cold
start emissions averaged 0.130 g/bhp-hr (around ten times higher than the hot UDDS) where the
hot/cold weighted emissions was 0.028 g/bhp-hr which is above the certified 0.02 g/bhp-hr
emission factor. More than 90% of the NOx emissions occurred in the first 50 seconds of the cold
UDDS test. Once the catalyst warmed up, the remaining portions of the cold UDDS test showed
low NOx emissions similar to the hot UDDS test. It is expected the real impact of the cold start
emissions is much lower than 1/7 weighting factor required by the regulations and would be
represented by 50 seconds divided by the actual shift time (typically more than 3600 seconds).
More research is needed to understand cold start emissions and their impact regionally. The cold
start emissions suggest hybrid stop-start technology may need electrically heated catalyst to
minimize potential warm-start emissions during long periods of electric only operation.
The other emissions such as carbon monoxide, particulate matter, nitrous oxide, and ammonia also
showed some differences compared to similar stoichiometric 2010 certified and NZ certified NG
vehicles tested by UCR. For example, the PM for the ISX12N was slightly higher than the NZ and
2010 certified NG engine (0.002 g/bhp-hr vs 0.001 g/bhp-hr), the ammonia was slightly lower ~50
ppm vs ~200 ppm, and N2O was about the same. 95% of the N2O cold start emissions resulted in
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the first 50 seconds. The methane emissions were notably lower in both NZ engines tested
compared to the 2010 certified NG engine. The lower methane emissions may be a result of the
closed crankcase ventilation system. The fuel economy also appeared to be similar to previous
versions where the UDDS showed the lowest CO2 emissions and were below the current FTP
standard of 555 g/bhp-hr for both the cold start and hot start tests during in-use chassis testing.
Figure ES-2 Real-time NOx accumulated mass for the three UDDS hot cycles 1 Individual accumulated and integrated EF for the UDDS cycle is shown in the figure above.
The average of these tests is represented in Figure ES-1, UDDS cycle (0.0112 g/bhp-hr).
The Particle Number (PN) emissions for the ISX12N averaged from 2e14 #/mi for low power
cycles (Near Dock and ARB Creep) to ~8e12 #/mi for the ARB Cruise and Regional port cycles
(2.5 nm D50). The particle size distribution showed a peak concentration at 60 nm for all the hot
start tests. On average about 50% of the particle number emissions were solid particles for all the
test cycles evaluated. The ISX12N #/mi PN emissions were similar to the 2010 certified and the
NZ certified engine (~8e12 #/mi). As such, PN emissions from NG vehicles tends to be higher (by
about 80x) compared to a diesel’s equipped with diesel particulate filters (~1e11 #/mi).
Summary: In general the ISX12N NG engine hot start emissions were within the 0.02 g/bhp-hr
certification standard for all the cycles tested, but the cold start combined emissions were high.
The optional Low NOx emission factor was maintained for the full range of hot-start duty cycles
found in the South Coast Air Basin unlike other heavy-duty diesel fueled technologies. The other
gaseous and PM emissions were similar if not lower to previous studies. It is expected NG vehicles
with the ISX12N could play a role in the reduction of the south coast NOx inventory in future years
given the near zero emission factors demonstrated on each test cycle. Unregulated particle number
and ammonia emissions, and regulated methane emissions were higher than current 2010 certified
diesel engines. These emissions should be considered when evaluating environmental and health
impacts.
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1 Background
1.1 Introduction
Heavy duty on-road vehicles represent one of the largest sources of NOx emissions and fuel
consumption in North America. Heavy duty vehicles are predominantly diesels, although there is
increasing interest in natural gas (NG) systems. As emissions and greenhouse gas regulations
continue to tighten new opportunities for advanced fleet specific heavy duty vehicles are becoming
available with improved fuel economy. At the same time NOx emissions have dropped 90% for
heavy duty vehicles with the recent 2010 certification limit. Additional NOx reductions of another
90% are desired for the South Coast Air basin to meet its 2023 NOx inventory requirements. Thus,
an approach to reduce emissions also needs lower fuel consumption to the extent possible.
1.2 NOx Emissions
Although the 2010 certification standards were designed to reduce NOx emissions, the in-use NOx
emissions are actually much higher than certification standards for certain fleets. The magnitude
is largely dependent on the duty cycle. Since engines are certified at moderate to high engine loads,
low load duty cycle can show different emission rates. For diesel engines low load duty cycles
have a significant impact in the NOx emissions. The NOx cold start emissions for the first 100
seconds were over 2.2 g/hp-h where for the same time frame with the hot cycle it was 0.006 g/hp-
h1, see Figure 1-1. The cold start emissions were ten times higher than the certification standard
and much higher than the corresponding hot start emissions. Additionally the stabilized emission
of the two systems over the same time period was very similar at 0.05 g/hp-h (about 75% below
the standard). The main cause for the high NOx emissions is low selective catalytic reduction (SCR)
inlet temperatures resulting from low power operation.
Figure 1-1 Engine dynamometer NOx and PM certification emissions standards (source CWI)
1 Wayne Miller, Kent C. Johnson, Thomas Durbin, and Ms. Poornima Dixit 2013, In-Use Emissions Testing and Demonstration of Retrofit
Technology, Final Report Contract #11612 to SCAQMD September 2013.
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These same trucks were tested on cycles designed to simulate port activity2. The port driving
schedule represents near dock (2-6 miles), local (6-20 miles), and regional (20+ miles) drayage
port operation. The SCR was inactive for 100% of the near dock cycle, 95% of the local cycle, and
60% of the regional cycle, see Figure 1-2. The NOx emissions were on the order of 0.3 to 2 g/hp-
h (1 to 9 g/mi) as much as 10 times higher than the 2010 standards. It has been show that the SCR
system also becomes inactive even after hours of operation due to low loads and lean compression
ignition combustion. Thus, the current diesel 2010 solution for low duty cycle activity (like at ports)
is very poor where a NG solution can make significant improvements for NOx emissions, and a
reduction in carbon emissions (carbon dioxide), but at a slight penalty in equivalent gallon diesel
fuel economy.
Figure 1-2 In-use emissions from a heavy duty truck tested on UCR’s chassis dyno
1.3 Fuel economy
Fuel consumption and emissions are a tradeoff due to the science of combustion. Figure 1-3 shows
the NOx emissions change with changes in fuel consumption for a typical spark ignited engine. As
NOx is reduced from 0.14 to 0.02 g/hp-h fuel consumption increases a known amount. This is a
result of the stoichiometric combustion of fuels. Advanced catalysts can be used to reduce NOx
from its baseline levels, but trying to reduce NOx within a fixed SI combustion system will come
at a penalty of increased fuel consumption.
Figure 1-3 NOx emissions versus fuel consumption tradeoffs during certification testing
2 Patrick Couch, John Leonard, TIAX Development of a Drayage Truck Chassis Dynamometer Test Cycle, Port of Long Beach/ Contract HD-7188,
2011
(Source CWI)
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1.4 Objectives
The goals of project are to evaluate the ISX12N NG ultra-low NOx NG vehicle emissions, global
warming potential, and fuel economy during in-use conditions. Given the low NOx concentrations
expected, advanced measurements were utilized to quantify NOx emissions at and below 0.02
g/bhp-hr emissions levels for NG engines. This report is a summary of the approach, results, and
conclusions of ultra-low NOx NG vehicle evaluation.
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2 Approach The approach for this demonstration vehicle evaluation includes in-use testing on a chassis
dynamometer, emissions measurements with UCRs mobile emission laboratory (MEL),
improvements to the NOx measurement method and a representative selection of in-use test cycles.
One of the difficulties in quantifying NOx emissions at the levels proposed in this project (90%
lower than the 2010 certification level ~ 0.02 g/bhp-hr) is the measurement methods are
approaching their detection limit to accurately quantify NOx emissions. This section describes the
test article, laboratories and the upgrades performed to quantify NOx emissions at and below 90%
of the 2010 emission standard.
2.1 Test article
2.1.1 Engine
The test article is the ISX12N 400 Cummins Westport Inc. (CWI) 11.9 liter Natural Gas engine
(SN = 75053847), see Table 2-1 for specifics and Appendix F for additional details. The engine
was developed to meet CARB’s optional ultra-low NOx standard of 0.02 g/bhp-hr (90% below the
2010 NOx emissions standard), see Figure F1 Appendix F.
Table 2-1 Summary of selected main engine specifications
Mfg Model Year Eng. Serial No Rated Power (hp @ rpm)
Disp. (liters)
Adv NOx Std g/bhp-h 1
PM Std. g/bhp-h
CWI Alpha X12N
2018 75053847 400 @ 1800 11.9 0.02 0.01
1 The family JCEXH0729XBC represents a 0.02 g/bhp-hr NOx standard, see Appendix F Figure 1 for details.
2.1.2 Test Fuel
California liquid natural gas (LNG) pipeline fuel was used for this study which represents typical
Natural Gas available in Southern California. The fuel properties were measured during the
emissions testing and are presented in Table 2-2. Fuel samples were collected from the vehicle
prior to testing. Three vehicle refuelings (Agua Mansa Station, Riverside CA) were required to
complete the work and three fuel samples were collected. The samples were analyzed and
presented in Table 2-2. The station LNG fuel varied in methane from 95.9 to 89.3 mole percent.
Table 2-2 Fuel properties for the local NG test fuels utilized
Property Molar % #1/#2 Property Molar % #1/#2
Methane 95.9 / 89.3 Pentane <0.001
Ethane 1.53 / 4.31 Carbon dioxide 0.00
Propane 0.032/0.079 Oxygen 0.45 / 0.08
Butane <0.003 Nitrogen 2.0 / 6.26 1 Based on these fuel properties, the HHV is 1042.5 BTU/ft3 and the LHV is 939.9 BTU/ft3 with a H/C ratio of 3.905,
a MON of 132.39 and a carbon weight fraction of 0.745 and a SG = 0.58, see Appendix E for laboratory results. Note
these results meets the US EPA 40 CFR Part 1065.715 fuel specification for NG fueled vehicles. #1 fuel was used on
1/30, 1/31, and 2/1 and test fuel #2 was used on 2/2 and 2/5 as listed in Appendix A.
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2.1.3 Vehicle inspection
Prior to testing, the vehicle was inspected for proper tire inflation and condition, vehicle condition,
vehicle securing, and the absence of any engine fault codes. The vehicle inspection and securing
met UCR’s specifications. The vehicle arrived at UCR with an active engine fault. Cummins
Westport Inc. had a Cummins Cal Pacific technician service the engine fault which turned out to
be a faulty oxygen sensor. The technician replaced the oxygen sensors prior to testing and the
engine fault was cleared and the vehicle was driven to make sure adaptive learning were complete.
No engine faults were found during or after testing was completed.
All tests were performed with-in specification and without any engine code faults. Thus, the results
presented in this report are representative of a properly operating vehicle, engine, and
aftertreatment system. At the time of testing the vehicle had 56,424 miles accumulated.
2.1.4 Test cycles
The test vehicle utilized an ISX12N NG engine which is primarily a goods movement engine in
the South Coast Air Basin. As such, UCR tested the vehicle following the three drayage type port
cycles (Near Dock, Local, and Regional), the Urban Dynamometer Driving Schedule (UDDS),
and the Heavy-Heavy Duty Diesel Truck (HHDDT) transient test cycles. These cycles are
representative of Sothern California driving vocations. Some cycles are very short (less than 30
minutes) where double or triple (2x or 3x) cycles are recommended in order capture enough PM
mass to quantify emissions near 1 mg/bhp-hr. The average speed of the cycles varies from 1.75
mph (HHDDT_CREEP) to 39.6 mph with an overall top speed on just under 70 mph
(HHDDT_Cruise), see Table 2-3 and Appendix B for details.
Table 2-3 Summary of statistics for the test cycles performed
Day Distance (mi) Average Speed (mph) Duration (sec) UDDS_CS 5.55 18.8 1061
UDDSx2 11.1 18.8 2122
Near Dock 5.61 6.6 3046
Local 8.71 9.3 3362
Regional 27.3 23.2 3661
HHDDT_Creepx3 0.372 1.75 768
HHDDT_Transx3 8.55 15.4 2004
HHDDT_Cruise 23.1 39.9 2083 1 Hot UDDS was performed as a double cycle (2x) and a single (1x) for the cold tests. The CBD was performed as a
triple (3x) test. The refuse cycle includes a compaction element where no distance is accumulated, but emissions are
counted with a simulated compaction cycle, see Appendix B for details.
2.1.5 Work calculation
The reported emission factors presented are based on a g/bhp-hr and g/mi basis (g/mi are provided
in Appendix E). The engine work is calculated utilizing signals from the engine ECM referred to
as J1939 actual torque, friction torque, and reference torque (1770.15 ft-lb). The following two
formulas show the calculation used to determine engine brake horse power (bhp) and work (bhp-
hr) for the tested vehicle. Distance is measured by the chassis dynamometer and the vehicle
broadcast J1939 vehicle speed signal. A representative ISX12N 400 engine lug curve is provided
in Figure 2-1.
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𝐻𝑝_𝑖 = 𝑅𝑃𝑀_𝑖(𝑇𝑜𝑟𝑞𝑢𝑒𝑎𝑐𝑡𝑢𝑎𝑙_𝑖 − 𝑇𝑜𝑟𝑞𝑢𝑒𝑓𝑟𝑖𝑐𝑡𝑖𝑜𝑛_𝑖)
5252∗ 𝑇𝑜𝑟𝑞𝑢𝑒𝑟𝑒𝑓𝑒𝑟𝑒𝑛𝑐𝑒
Where:
Hp_i instantaneous power from the engine. Negative values set to zero
RPM_i instantaneous engine speed as reported by the ECM (J1939)
Torque_actual_i instantaneous engine actual torque (%): ECM (J1939)
Torque_friction_i instantaneous engine friction torque (%): ECM (J1939)
Torque_reference reference torque (ft-lb) as reported by the ECM (J1939)
𝑊𝑜𝑟𝑘 = ∑𝐻𝑝_𝑖
3600
𝑛
𝑖=0
Figure 2-1 Published ISX12N Natural Gas engine torque curve
Figure 2-2 and Figure 2-3 show the measured power and work for each of the tests performed on
the heavy duty truck. Heavy duty engines are certified on the FTP type of cycle where the average
power is around 100 Hp and estimated at 33 bhp-hr (25% of rated). The UDDS and HHDDT Cruise
test cycles represent power near the FTP certification cycle. The other cycles showed lower power
with the HHDDT_Creep and Near Dock being the lowest (as shown by previous studies). One
concern for low power operation is higher NOx emissions as diesels aftertreatment systems are
not active. The TWC stoichiometric engine does not have this limitation and performed well for
all the cycles and is a success for NG engines. This will be discussed in the result section.
17
The measured work for the all the cycles (except the CBD (lower), RTC, and the regional (DPT3
much higher)) were close to the certification FTP estimated work (Note the hot-UDDS was higher
because a double cycle was performed where the cold-UDDS was performed as a single UDDS
test). In general the cycles selected are representative of in-use conditions and certification testing.
It is expected the results from this study will be very representative for real world emission factors
for the test article.
Figure 2-2 Power from the various tests with 1 stdev error bars 1 Error bars represent 1 standard deviation with a sample size of 3 (n=3). The error bars were higher than usual
due to ECM drop out. The engine CAN logging had some difficulties that caused more variability in the engine
load. The engine load will add to the uncertainty (around 3%) of the final results, but do not impact the overall
message of the low emission factors.
Figure 2-3 Work from the various tests with 1 stdev error bars 1 Error bars represent 1 standard deviation with a sample size of 3 (n=3). The error bars were higher than usual
due to ECM drop out. The engine CAN logging had some difficulties that caused more variability in the engine
load. The engine load will add to the uncertainty (around 3%) of the final results, but do not impact the overall
message of the low emission factors.
98.9793.40
43.14
52.90
82.24
34.69
85.43
107.22
0.0
20.0
40.0
60.0
80.0
100.0
120.0
CS UDDS UDDS NearDock
Local Regional HHDDTCreep
HHDDTTrans
HHDDTCruise
J 19
39 B
rake
Po
wer
(bhp
)
29.72
55.06
36.54
49.45
96.63
7.31
47.55
62.04
0.0
20.0
40.0
60.0
80.0
100.0
120.0
CS UDDS UDDS NearDock
Local Regional HHDDTCreep
HHDDTTrans
HHDDTCruise
J 19
39 B
rake
Wo
rk (b
hp
-hr)
18
2.2 Laboratory
The testing was performed on UC Riverside’s chassis dynamometer integrated with its Mobile
Emissions Laboratory (MEL) located in Riverside CA just east of the South Coast Air Quality
Management District (AQMD). This section describes the chassis dynamometer and emissions
measurement laboratories used for evaluating the in-use emissions from the demonstration vehicle.
Due to challenges of NOx measurement at 0.02 g/bhp-hr, additional sections are provided to
introduce previous measurement improvements and new measurement improvements for the
emissions testing performed in this report.
2.2.1 Chassis dynamometer
UCR’s chassis dynamometer is an electric AC type design that can simulate inertia loads from
10,000 lb to 80,000 lb which covers a broad range of in-use medium and heavy duty vehicles. The
design incorporates 48” rolls, vehicle tie down to prevent tire slippage, 45,000 lb base inertial plus
two large AC drive motors for achieving a range of inertias. The dyno has the capability to absorb
accelerations and decelerations up to 6 mph/sec and handle wheel loads up to 600 horse power at
70 mph. This facility was also specially geared to handle slow speed vehicles such as yard trucks
where 200 hp at 15 mph is common. See Appendix D for more details.
2.2.1.1 Test weight
The ISX12N 400 engine is installed in a heavy duty truck with a GVWR of 52,000 lb, VIN
1FUJGBD97FLFY9734. The representative test weight for goods movement operating in the
south coast air basin is 69,500 lb3. The testing weight of 69,500 lb was also utilized during previous
testing of several goods movement NG and diesel trucks by UC Riverside and WVU 4 and 4. For
this testing program, UCR utilized a testing weight of 69,500 lb for all test cycles (UDDS, port,
and ARB HHDDT).
2.2.1.2 Coast down
UCR utilizes a calculation approach for the coast down settings of the chassis dynamometer. This
approach is also used by other testing facilities and has been shown to be representative of in-use
operation, see Appendix G for a more detailed discussion. The selected test weight of 69,500 lb
resulted in a power of 107.34 Hp at 50 mph with the calculated dynamometer loading coefficients
of A = 493.6193, B = -3.3409E-14 and C = 0.124575. See calculation methods in Appendix G for
more details.
2.2.2 Emissions measurements
The approach used for measuring the emissions from a vehicle or an engine on a dynamometer is
to connect UCR’s heavy-duty mobile emission lab (MEL) to the total exhaust of the diesel engine,
see Appendix C for more details. The details for sampling and measurement methods of mass
emission rates from heavy-duty diesel engines are specified in Section 40, Code of Federal
Regulations (CFR): Protection of the Environment, Part 1065. UCR’s unique heavy-duty diesel
MEL is designed and operated to meet those stringent specifications. MEL is a complex laboratory
and a schematic of the major operating subsystems for MEL are shown in Figure 2-4. The accuracy
3 Wayne Miller, Kent C. Johnson, Thomas Durbin, and Ms. Poornima Dixit 2014, In-Use Emissions Testing and Demonstration of Retrofit
Technology, Final Report Contract #11612 to SCAQMD September 2014.
4 Daniel K Carder, Mridul Gautam, Arvind Thiruvengada,m Marc C. Besch (2013) In‐Use Emissions Testing and Demonstration of Retrofit
Technology for Control of On‐Road Heavy‐Duty Engines, Final Report Contract #11611 to SCAQMD July 2014.
19
of MEL’s measurements has been checked/verified against ARB’s 5 and Southwest Research
Institute’s6,7 heavy-duty diesel laboratories. MEL routinely measures Total Hydrocarbons (THC),
Methane (CH4), Carbon Monoxide (CO), Carbon Dioxide (CO2), Nitrogen Oxides (NOx), and
Particulate Matter (PM) emissions from diesel engines. Design capabilities and details of MEL are
described in Cocker et al4, 8 . Samples can be collected for more detailed analyses such as
hydrocarbon speciation, carbonyl emissions, polynuclear aromatic hydrocarbons, etc.
Figure 2-4 Major Systems within UCR’s Mobile Emission Lab (MEL)
2.2.3 Low NOx Measurements
The optional low NOx standard (< 0.02 g/bhp-hr) is approaching the measurement detection limits
for the traditional dilute CVS measurement method. In the previous Low NOx evaluation with the
ISL G Near Zero (NZ) 8.9L engine, UCR evaluated five methods two from the tradition approach
and three new methods, see Table 2-4 for summary of methods. The previous results showed more
than ½ of the measurements for the Ultra Low NOx NG engine had a dilute concentration 50% of
the ambient corrected concentration. The low diluted concentrations measured impact all the
methods except for M3 (raw) such that variability and means were different. Although there were
no statistical differences in that study, it was suggested the traditional (M1 and M2) and raw (M3)
5 Cocker III, D. R., Shah, S. D., Johnson, K. C., Zhu, X., Miller, J. W., Norbeck, J. M., Development and Application of a Mobile Laboratory for
Measuring Emissions from Diesel Engines. 2. Sampling for Toxics and Particulate Matter, Environ. Sci. Technol. 2004, 38, 6809-6816
6 Cocker III, D. R, Shah, S. D., Johnson, K. C., Miller, J. W., Norbeck, J. M., Measurement Allowance Project – On-Road Validation. Final Report
to the Measurement Allowance steering Committee.
7 Johnson, K.C., Durbin, T.D., Cocker, III, D.R., Miller, W.J., Bishnu, D.K., Maldonado, H., Moynahan, N., Ensfield, C., Laroo, C.A. (2009) On-
road comparison of a portable emission measurement system with a mobile reference laboratory for a heavy-duty diesel vehicle, Atmospheric
Environment 43 (2009) 2877–2883
8 Cocker III, D. R, Shah, S. D., Johnson, K. C., Miller, J. W., Norbeck, J. M., Development and Application of a Mobile Laboratory for
Measuring Emissions From Diesel Engines I. Regulated Gaseous Emissions, Environmental Science and Technology.
2004, 38, 2182-2189
20
measurement were recommended9. For details on the methods, calculations and evaluation see (5).
Method 4 and 5 were not used during this study.
Chemiluminescence Detection (CLD) is the laboratory method for dilute and raw NOx
measurement. The CLD analyzer measures the light (lumens) emitted by the reaction with NO and
Ozone (O3). Similarly NH3 will also react with O3 to emit light thus adding the response in a NOx
analyzer unless care is taken. Many in the industry add acid treaded filters to mask the effect, but
it is uncertain how well they work during high NH3 concentration and low NO concentrations. As
such, UCR integrated a quantum cascade laser (QCL) measurement method to evaluate the impact
of ultra-low NOx measurement in the presence of large amounts of NH3. The QCL is a
spectroscopy method which can measure NO and NO2 and is not sensitive to NH3 cross
interference.
Table 2-4 NOx measurement methods traditional and upgraded
Type Analyzer Meth. ID Description
Traditional 600 HCLD dil
600 HCLD amb M1 Modal NOx with ambient bag correction
Traditional 600 HCLD dil
600 HCLD amb M2 Dilute bag NOx with ambient bag correction
Upgrade 300 HCLD raw M3 Raw NOx no ambient bag correction
Upgrade 600 HCLD dil
TECO amb M4
Modal dilute NOx with ambient real time
correction
Upgrade TECO dil
TECO amb M5
Trace analyzer dilute bag with trace ambient bag
correction
This section discussed the traditional, raw and added QCL NOx measurement methods
recommended for the ultra-low NOx evaluation. This section also provides a section on the other
real time measurement methods utilized for particle number.
2.2.3.1 Traditional method
The traditional NOx measurements include a 600 heated chemiluminescent detector (CLD) from
California Analytical Inc. (CAI) configured to sample from the CVS tunnel during real time and
ambient and dilute bag measurements following automated routines of the MEL laboratory. The
samples are collected from the CVS dilute tunnel through an acid treated filter to prevent
measurement interferences from ammonia (NH3) concentrations. The acid treated filters were
replaced daily.
2.2.3.2 Method upgrades
Two NOx upgrade methods were considered for this project. These included 1) real-time raw CLD
sampling and exhaust flow measurements and 2) real-time raw QCL sampling and exhaust flow
measurements. The raw CLD sampling was setup in the previous program and the QCL was added
to the measurements from this program. The new measurement methods are discussed below.
Raw NOx measurements
The raw NOx measurements utilized a 300 HCLD CAI analyzer which sampled raw exhaust
through a low volume heated filter and heated sample line. The low volume design was considered
9 Johnson, K., Jiang, Y., and Yang, J., Final Report Ultra-Low NOx Natural Gas Vehicle Evaluation ISL G NZ, SC AQMD, November 2016.
21
to improve the response time of the analyzer with the exhaust flow measurement. The heated filter
was acid treated to minimize NH3 interference with the NOx measurement. A real-time high speed
exhaust flow meter (100 Hz model EFM-HS Sensors Inc) was used to align NOx concentration
with real time exhaust flow measurements. The EFM-HS was correlated with UCR dual CVS
system prior to testing to improve the accuracy between the raw and dilute CVS methods and
eliminate exhaust flow biases from propagating through the comparison.
Quantum Cascade Laser spectroscopy (QCL)
UCR utilized the MEXA-ONE-QL-NX Quantum Cascade Laser (QCL) analyzer for the direct,
simultaneous real-time measurement of the four relevant nitrogen-containing exhaust gas
components NO, NO2, N2O and NH3. The analyzer combines a light source based on the new
quantum cascade technology (efficient lasers in the mid-infrared spectral region) with a precisely
adjusted dual path cell to measure low concentrations with maximum sensitivity. The detection
limit complies with current European legal requirements. Furthermore, the MEXA-ONE-QL-NX
offers wide measuring ranges of up to 5000 ppm (for NO). By using extremely narrowband light
sources and measuring under reduced pressure the cross-sensitivity to other exhaust gas
components can be drastically minimized. The complete measuring system - including filtration -
is specifically developed for the measurement of NH3 and thus guarantees a very fast NH3 rise
time (T10-T90) of less than 5 seconds. The MEXA-ONE-QL-NX can be operated as a stand-alone
analyzer or integrated into the MEXA-ONE software interface for user-friendly and simplified
system operation.
2.2.3.3 Calculation upgrades
The calculations for the traditional and improved methods are presented in this section. The
calculations are in agreement with 40 CFR Part 1065, but are presented in a condensed version to
draw observation differences without the details of working in molar flow rates as per 40 CFR Part
1065. The calculations are provided in the previous report and are not repeated here.
Table 2-5 NOx measurement methods traditional and upgraded
Type Analyzer Meth. ID Description
Traditional 600 HCLD dil
600 HCLD amb M1 Modal NOx with ambient bag correction
Traditional 600 HCLD dil
600 HCLD amb M2
Dilute bag NOx with ambient bag
correction
Previous 300 HCLD raw M3 Raw NOx no ambient bag correction
Upgrade QCL raw M3b Raw NO, NO2, N20, and NH3
2.2.3.4 Method evaluation
The evaluation of the methods in this report include the dilute, raw CLD and raw QCL. For the
dilute CVS measurements, one of the main contributing factors is the magnitude of the ambient
concentration has on the calculation. As discussed previously, the 50th percentile raw, dilute, and
ambient NOx concentration were 0.55 ppm, 0.17 ppm, and 0.07 ppm respectively. This analysis
will not be repeated here, but is expected to be similar since emission levels were similar and the
same configuration for the dilute CVS was utilized.
22
The raw accumulated CLD NOx emissions is compared to the raw accumulated QCL NOx
emissions in Figure 2-5. The two NOx measurement methods CLD and QCL track well and there
is no obvious deviation for the CLD NOx measurement resulting from the high NH3 emissions,
see Figure 2-5. In addition, the integrated results between the raw CLD and raw QCL show the
CLD is slightly lower (20%) than the QCL when all the integrated results are pooled together, see
Figure 2-7 and Figure 2-8. If there were an interference for the CLD it would have increased the
measurement not reduced it. Thus, both the real time figure and the integrated results suggest the
CLD interferences from the high concentration NH3 is not causing a measurable impact on the
CLD measurement when acid treated filters are used and replaced on a daily basis in the presence
of 50 to 300 ppm raw NH3.
The comparison between the integrated NOx measurement methods showed no statistical
differences in means between the different methods except between raw CLD and raw QCL, see
Table 2-6. The two tailed paired t-test between raw CLD and raw QCL was 0.02 suggesting the
means are statistically different and the raw CLD NOx was on average 20% lower than the QCL
NOx. There were not differences in variability or in means for the rest of the comparisons.
Figure 2-5 Real time raw (CLD and QCL) accumulation NOx with NH3 concentration
23
Figure 2-6 Real time raw (CLD and QCL) and dilute CLD NOx measurements
Figure 2-7 Measured NOx emission for the hot and cold start test cycles
24
Figure 2-8 Measured NOx emission for the hot start only test cycles
Table 2-6 NOx measurement methods t and f test (paired, two tailed) statistics
2.2.4 NH3, PN, PSD, and BC Measurements
In addition to the regulated emissions, the laboratory was equipped to measure particle size
distribution (PSD) with TSI’s Engine Exhaust Particle Sizer (EEPS) model 3090, particle number
(PN) with a TSI 3776 condensation particle counter (CPC), a PN measurement system with a
catalytic stripper (CPC_CS), soot PM mass with AVL’s Micro Soot Sensors (MSS 483) which
reports equivalent black carbon (eBC), and ammonia (NH3) emissions with an integrated real-time
tunable diode laser (TDL) from Unisearch Associates Inc.
The PN measurement system used a low cut point CPC (2.5 nm D50) because of the large PN
concentrations reported below the PMP protocol CPC 23 nm measurement system (10, 11, and
12). The EEPS spectrometer displays measurements in 32 channels total (16 channels per decade)
and operates over a wide particle concentration range, including down to 200 particles/cm3.
-0.015
-0.010
-0.005
0.000
0.005
0.010
0.015
0.020
0.025
0.030
0.035
0.040
UDDS Near Dock Local Regional HHDDTCreep
HHDDTTrans
HHDDTCruise
NO
x E
mis
sio
ns
(g/b
hp-
hr)
CLD_dilute CLD_raw QCL_raw CLD_dilute_bag
Array 1 Array 2 aves all aves all
raw CLD dil CLD 0.226 0.128 0.599 0.777
dil CLD raw QCL 0.374 0.268 0.374 0.241
raw CLD raw QCL 0.085 0.021 0.725 0.360
dil CLD bag CLD 0.955 0.921 0.808 0.661
raw CLD bag CLD 0.533 0.249 0.454 0.470
raw QCL bag CLD 0.493 0.405 0.256 0.117
t.test f.test
25
3 Results
This section describes the results from the ISX12N NG ultra-low NOx NG engine. The results are
organized by gaseous emissions followed by PM, particle number (PN), particle size distribution
(PSD), greenhouse gases, and fuel economy. The emission factors presented in g/bhp-hr for
comparison to the certification standard. Emissions in g/mile are provided in Appendix E. Error
bars are represented by single standard deviations.
The UDDS cycle is the representative test cycle for comparisons to the engine certification FTP
cycle where the other cycles (port and CARB HHDDT) provide the reader a feel for the in-use
comparability to low duty cycles, cruise conditions, and other vocational specifics of the real
world. As such, the results will be presented in each sub-section within the context of the test cycle.
3.1 Gaseous emissions
The results section is organized similar to the 2015 report on the ISL9N NZ NG engine. This
includes utilizing similar scaling for each of the figures and the organization of the sections. The
goal was to be able to compare the reports side-by-side to draw conclusions between the two
demonstrations.
3.1.1 NOx emissions
The NOx emissions are presented in Figure 3-1 for the raw CLD method for all the test cycles
performed (hot and cold). NOx emissions were below the demonstration 0.02 g/bhp-hr emissions
targets for the all the hot start tests (Note rounding the HHDDT results becomes 0.02 g/bhp-hr).
The NOx emissions did not increase with decreasing load as is common with diesel engines
(similar result for the ISL G NZ 8.9L engine). As discussed previously this is a result of the
stoichiometric fuel control and TWC aftertreatment system. The port emissions ranged from 0.012
to 0.006 g/bhp-hr and the ARB HHDDT varied from 0.001 to 0.02 g/bhp-hr. The cold start
emissions were higher than the hot tests when comparing between like tests (UDDS cold vs hot)
and averaged at 0.130 g/bhp-hr for the UDDS test cycle. The previous ISL9N NZ engine showed
a lower cold start 0.043 vs 0.13 g/bhp-hr) and about the same hot start emissions compared to the
ISX12N engine.
In general, the NOx emissions are below the ISX12N 2018 optional low NOx certification standard
of 0.02 g/bhp-hr for all tests but one and below the in-use NTE standard of 0.03 g/bhp-hr. The
reported certification value listed on the ARB EO is 0.01 g/bhp-hr which is slightly lower than the
M3 measurements (0.0112 g/bhp-hr) shown for the UDDS hot test cycle, Figure 3-1. Deeper
investigation shows all the tests had similar NOx spikes resulting from de-acceleration, more
discussion is presented in a later section. The same NOx spike was also found for the other
measurement methods. The test-to-test variability shown by the error bars in Figure 3-1 was
investigated where real-time analysis suggest the variability is not from low measurement issues,
but appears to be the results of the vehicle variability. Section 4 provides a discussion on real-time
investigation.
26
Figure 3-1 Measured NOx emission for the hot and cold start test cycles
3.1.2 Other gaseous emissions
The hydrocarbon emissions (THC, CH4, and NMHC) are presented in Figure 3-2. The THC were
relatively consistent between test cycles and ranged between 0.4 b/bhp-hr (CS_UDDS) and 0.01
g/bhp-hr (HHDDT Trans). The regulated HC species (NMHC) ranged from less than zero
(truncated to zero) to 0.03 g/bhp-hr for the CS_UDDS. For all the tests (hot and cold) the NMHC
was below the standard (0.14 g/bhp-hr) and above the reported certification value in the EO (0.004
g/bhp-hr), Appendix F Figure F-4. The NMHC was typically lower than CH4 emission as one
would expect for a NG fueled vehicle. Also the CH4 emissions for the heavy duty truck are
significantly lower (6.4 g/mi vs 0.9 g/mi UDDS) than previously tested NG trucks with the 2010
certified ISL G 8.9 L engine. The lower CH4 emissions may be a result of the closed crankcase
ventilation (CCV) improvement over previous versions of this engine.
0.1302
0.0112 0.0093 0.00640.0124
0.0012
0.0205
0.0081
0.00
0.02
0.04
0.06
0.08
0.10
0.12
0.14
0.16
CS UDDS UDDS Near Dock Local Regional HHDDTCreep
HHDDTTrans
HHDDTCruise
NO
x Em
issi
ons
(g/b
hp
-hr)
0.02 g/bhp-hr Optional Low NOx Standard
27
Figure 3-2 Hydrocarbon emission factors (g/bhp-hr)
Figure 3-3 shows the CO emissions on a g/bhp-hr basis and Figure 3-4 shows the un-regulated
NH3 emissions on a g/bhp-hr basis. Figure 3-5 shows the NH3 emissions in concentration. The CO
emissions ranged between 0.23 (HHDDT_Trans) to 1.93 g/bhp-hr (CS_UUDS). The distance
specific emissions ranged from 0.38 g/mi (Cruise) to 2.7 g/mi (Creep) which is lower than previous
testing of NG vehicles from CWI (both the 2010 certified and the optionally low NOx engine
tested by UCR in 2015). Previous testing of the ISL G (2010 certified engine) showed CO
emissions ranging from 14.4 to 19.2 g/mi (CBD and UDDS test cycles).
28
Figure 3-3 CO emission factors (g/bhp-hr)
The NH3 emissions ranged from 0.038 (Trans) to 0.18 g/bhp-hr (CS_UUDS). The distance specific
emissions varied from 0.015 g/mi (Local) to 0.34 g/mi (Creep) for the regional and CBD test
cycles. The NH3 emissions are much lower than previous ISL G (2010 certified) and NZ vehicles
where the NH3 ranged from 1.17 to 2.8 g/mi for the UDDS and RTC (2010 certified) and from
1.19 and 4.09 g/mi for the NZ certified, respectively. The ISX12N NH3 emissions varied from
20.1 ppm (Trans) to 54.8 ppm (Near Dock) which is almost a magnitude of order lower than before,
see Figure 3-5.
Figure 3-4 Ammonia emission factors (g/bhp-hr)
1 NH3 are based on the QCL system sampling from the raw exhaust. Similar results were found with UCR’s
integrated TDL.
1.93
1.28
0.74 0.74 0.760.83
0.23
0.81
0.0
0.5
1.0
1.5
2.0
2.5
CS UDDS UDDS Near Dock Local Regional HHDDTCreep
HHDDTTrans
HHDDTCruise
CO E
mis
sio
ns (g
/bhp
-hr)
29
Figure 3-5 Ammonia measured tail pipe concentration (ppm)
1 NH3 are based on the QCL system sampling from the raw exhaust. Similar results were found with UCR’s
integrated TDL.
3.2 PM emissions
The PM emissions for all the tests including the cold start tests was typically 80% below the
certification standard (0.010 g/bhp-hr), see Figure 3-6. The total PM emissions reported as PM2.5
ranged from 0.004 g/bhp-hr (CS_UDDS) to 0.001 g/bhp-hr (Regional). The emissions are slightly
higher than the previous NZ demonstration and it is suggested this may be a result of some added
oil consumption. A discussion in the Ultrafine Section will be utilized to facilitate this discussion.
In general, the low PM results are expected for a NG fueled engine where previous studies showed
similar PM emissions well below 10 mg/bhp-hr.
The measured filter weights were 51 ug with a single standard deviation of 23 ug where the tunnel
blank ranged from 5 - 8 µg. As such, the PM emission rates were low and near the quantification
limit of PM filters (ten times the LDL = 10*6 µg = 60 µg/filter), see Figure 3-7. The shown
variability may be a result of measurement detection more than vehicle performance between
cycles.
30
Figure 3-6 PM emission factors (g/bhp-hr)
1 Creep, transient and cruise cycles were shorter than the port cycles and thus had more variability due to the filter
weight. See figure below.
The soot or elemental carbon denoted as equivalent black carbon (eBC) ranged from
0.0004 g/bhp-hr (CS_UDDS) to 0.0024 g/bhp-hr (Creep). The Creep cycle emissions
were only large because the work (denominator) was so small. When you consider the
MSS-483 measured concentration the emissions were more consistent between the hot
tests and averaged 0.079 mg/m3 (LDL is 0.002 mg/m3 for the MSS-483).
Figure 3-7 PM emission measurements filter weights and eBC concentration 1 Tunnel blanks were 5-8 ug during this project and filter weights below 0.05 mg are near quantification limits
(10*LDL = 0.050 mg/filter). When close to the quantification limits the variability may be a result of
measurement detection and not test article. eBC concentrations were also near quantification limits (10 * LDL =
10*0.002 or 0.020 mg/m3).
0.0036
0.0018 0.0015 0.00150.0011
0.0040
0.0013 0.0012
0.000
0.002
0.004
0.006
0.008
0.010
0.012
0.014
CS UDDS UDDS NearDock
Local Regional HHDDTCreep
HHDDTTrans
HHDDTCruise
PM E
mis
sion
s (g
/bhp
-hr)
PM2.5 eBC
31
3.3 PN emissions
The PN emissions utilizing a low cut point CPC (3772) are shown in Figure 3-8 and Table 3-1 for
both total and solid (with a catalytic stripper) number per mile. The total PN (CPC_total) were
highest (2e14) for the Creep cycle (HHDDT_Creep) and lowest on the Regional and Cruise cycles
(~8e12). Since the UDDS cycle is representative of the FTP certification like cycle, comparisons
to the hot UDDS are considered. The cold start total PN was higher than the hot cycle and showed
a trend of increasing total PN (#/mi) as you decrease load. When you look at the measured
concentration (Figure 3-9), the PN emissions are relatively flat suggesting the PN emissions are at
a constant rate from the exhaust so slow traffic will experience higher PN emissions from the
vehicle.
During previous studies with 0.2 g/bhp-hr certified NOx ISL G engine tested on the near dock and
regional port cycles, the PN emissions were 1.9x1012 ± 3.8 x1011 #/mi (11) which was about 92%
lower than the ISX12N UDDS test cycle results, but about the same as the near dock port cycle.
In a second study with the ISL G NZ 8.9 liter engine, the PN emissions were 4x1012 for the CBD
test cycle (10) which agrees well with the results in this study for the near dock test cycles. During
a similar refuse hauler application of the ISL G engine, the PN emissions for the RTC cycle were
2.5x1013, 5.8x1012, and 2.0x1012 #/mi for the curbside, transit, and compaction portions of the RTC
test cycle, respectively (12) which compare well with the PN from the ISX12N results. Late model
diesel engines equipped with DPFs show PN emissions (with similar D50 cut points of 2.5 nm)
ranged from 1.3x1011 to 0.7x1011 for on-road UDDS and cruise type of tests (18). In general the
PN emissions for the ISX12N are mixed in comparison to the ISL G with some higher and some
about the same. The ISX12N and ISL G both show higher (10x to 1000x higher) PN emissions
compared to diesel vehicles equipped with DPFs.
Figure 3-8 Particle number emissions solid and total (#/mi)
1 Note the PN presented are based on CVS dilute measurements with and without sample conditioning using a
catalytic stripper (CS). These data represent total particles (without CS) and solid particles (with CS). The CPCs used
were based on a D50 of 2.5 nm (CPC 3776). These PN values may be higher than those presented by the PMP system
which uses a 3790A counter (24 nm D50 cut diameter) and a volatile particle CS system.
32
Table 3-1 PN Emissions from the ISX12N engine for various cycles
1 CS stands for cold start and Stdev is a single standard deviation (n=3)
The solid particles are also considered in this study which were not considered in the previous
study of the NA engine. The solid particles are quantified by removing the semi-volatiles with a
catalytic stripper in front of the CPC. The solid PN were lower than the total PN as expected where
the solid PN fraction represented on average 50% of the total PN, see Figure 3-10. The percent
solid particle was highest for the near dock and lowest for the regional cycle (71% vs 52%)
suggesting as duty cycle increases in load the fraction of solid particles reduces. The opposite trend
was observed for the CARB HHDDT cycles.
Figure 3-11 shows a comparison between the EEPS measurement system and the total and solid
PN CPC measurement systems for selected test cycles. The EEPS and total CPC PN were in
agreement where their correlation resulted in a slope of 0.56 (EEPS slightly lower than the CPCs)
with an R2 of 0.995.
Figure 3-9 Particle number emissions solid and total (#/cc)
1 Note the PN presented are based on CVS dilute measurements with and without sample conditioning using a
catalytic stripper (CS).
Trace Power Distance
n/a bhp mi ave stdev ave stdev
CS UDDS 99.0 5.7 3.0E+13 7.8E+12 1.3E+13 3.9E+12
UDDS 93.4 11.4 1.1E+13 2.7E+12 8.0E+12 4.8E+11
Near Dock 43.1 5.8 2.9E+13 4.2E+12 2.0E+13 3.3E+12
Local 52.9 8.9 1.9E+13 1.3E+12 1.1E+13 6.6E+11
Regional 82.2 27.6 8.7E+12 1.9E+12 4.4E+12 5.6E+11
HHDDT Creep 34.7 0.4 2.2E+14 3.4E+13 6.8E+13 2.3E+13
HHDDT Trans 85.4 8.9 1.8E+13 1.6E+12 8.1E+12 1.1E+12
HHDDT Cruise 107.2 23.2 7.6E+12 1.0E+12 2.8E+12 4.0E+11
Total_PN #/mi Solid_PN #/mi
33
Figure 3-10 Percent solid particle number from CPC data (%)
Figure 3-11 EEPS comparisons for PN (#/mi)
1 EEPS #/mile estimate using traditional inversion matrix provided with EEPS. Note
3.4 Ultrafines
The ultrafine PSD (as measured by the EEPS) are shown in Figure 3-12 on a log-log scale
concentration basis as measured in the dilute CVS. The cold start UDDS cycle showed the highest
particle number concentration at ~10 nm particle diameter where all the hot tests (UDDS, Port,
and HHDDT) all showed very similar PSD. The higher PSD for the cold UDDS and regional cycle
are a result of a PN spike near the last hill of the UDDS test cycle.
Although it is hard to see from the figure, there is a secondary peak at 60 nm particle diameter
which was not evident during the previous testing of the NZ technology. The PN at 60 nm is ~
34
4E5 #/cc where previously it was < 1E4 and ranged from 5E3 to 1E2 at similar CVS sample
conditions. The higher PM mass (average filter weights of 50 vs 20 ug) suggests there may be
higher PM mass emissions. It is suspected the PM emissions from NG vehicles is from the
lubrication oil. Diesel vehicles equipped with a DPF only show a single mode of operation (when
not in a DPF regeneration) for the same UDDS and port cycles tested on the ISX12N vehicle (2).
Figure 3-12 EEPS ultrafine PSD CVS measurements for each of the test cycles
3.5 Greenhouse gases
The greenhouse gases include CO2, CH4 and N2O and are reported here to characterize the vehicles
global warming potential (GWP). The GWP calculations are based on the intergovernmental panel
on climate change (IPCC) values of 25 times CO2 equivalent for CH4 and 298 times CO2 equivalent
for nitrous oxide (N2O), IPCC fourth assessment report - 2007. The global warming potential is
provided in Table 3-2 on a g/bhp-hr basis (see Appendix E for g/mi basis). The CH4 and N2O
emissions are low and represent less than 3% for the cold start tests and around 1% for the hot start
tests.
N2O showed up to 1% contribution to the GWP for the cold start, but less than 0.02% for all the
hot starts where CH4 represented from 2% to 0.1% for the various cycles. The higher cold start
N2O emissions was a result of a large N20 spike at the start of the test, see Figure 3-13. N2O reached
200 ppm for the first 50 seconds and this one spike represented 95% of the total N20 emissions
for the full test cycle. This observation was only possible due to the advanced QCL technology
developed by Horiba. The hot start UDDS did not result in a large N20 spike during a warm start
with the catalyst temperature of approximately 350 C (see Figure 3-14). Others have shown (Huai
et al, 2003) that N20 emissions can exist from a warm start gasoline TWC controlled vehicle. NG
60 nm ~ 5 E4 #/cc
35
cold start and warm start N20 emissions may be a concern if frequent cranking events occur.
Analysis of the vehicle activity is needed to truly assess the impact of NG emissions on the region.
Greenhouse gases from vehicles are also found in PM emissions for their absorption of solar
radiation. The main species of the PM responsible for solar absorption is called black carbon (BC).
BC is a short-lived climate forcer and is not grouped with the CO2 equivalent method, and is treated
here separately. UCR quantified the BC emissions (referred to as equivalent black carbon eBC)
from the vehicle with its AVL micro soot sensor 483 (MSS) which measures the PM soot or eBC.
Table 3-2 lists the soot PM for each cycle and the ratio of soot/total PM emissions. The results
suggest around 10% of the cold start PM is eBC and up around 50% of the hot start cycles are
eBC. Additional analysis showed that the measured average concentration ranged between 59
ug/m3 which is an order of magnitude higher than for the previous NZ technology tested. The
higher concentrations suggests there is more PM and eBC for the ISX12N compared to the ISL9N.
Table 3-2 Global warming potential for the ISX12N truck tested (g/bhp-hr)
1 N20 samples were not collected on the hot UDDS, RTC, and DPT1 due to scheduling details. PM Soot
measurements were near the detection limits of the MSS-483 measurement system. The MSS soot signal was
corrected for a 1 ug/1% water interference factor as reported by AVL.
Trace CO2 CH4 N20GWP
(CO2 eq)eBC eBC/PM2.5
CS UDDS 540.5 0.434 0.0192 557.1 0.0004 12%
UDDS 534.1 0.180 0.0000 538.6 0.0007 42%
Near Dock 608.5 0.181 0.0001 613.0 0.0009 59%
Local 611.3 0.137 0.0001 614.7 0.0008 53%
Regional 555.4 0.408 0.0005 565.7 0.0007 62%
HHDDT Creep 612.0 0.369 0.0001 621.2 0.0024 59%
HHDDT Trans 548.7 0.018 0.0001 549.2 0.0005 42%
HHDDT Cruise 534.4 0.349 0.0003 543.3 0.0008 64%
36
Figure 3-13 QCL N20 Results during a cold start
Figure 3-14 QCL N20 Results during a hot start (N20 Multiplied by 100)
3.6 Fuel economy
The fuel economy of the NG vehicle is evaluated by comparing the CO2 emissions between cycles
where the higher the CO2 the higher the fuel consumption. CO2 is also regulated by EPA with a
standard as performed with the FTP and SET test cycles. The certification like cycle (UDDS)
showed the lowest CO2 emissions and were below 555 g/bhp-hr (FTP standard) for both the cold
start and hot start tests. The NG vehicle CO2 emissions varied slightly between cycles where the
light loaded cycles (Near Dock, Local, and Creep) showed a higher CO2 emission compared to the
FTP standard. The average CO2 for all the cycles was 568 g/bhp-hr, and 542 g/bhp-hr with the low
power cycles removed. The CO2 standard and certification value is 555 g/bhp-hr and 502 g/bhp-
hr respectively for this displacement engine, see Figure F1 Appendix F. The standard is the target
and the certification value is the value measured (for a particulate engine rating which is defined
in 1065) by the manufacturer. It is suggested the higher in-use CO2 value (ie in the chassis vs on a
test stand) could be a result of additional losses in the chassis where the certification test occurs
with the engine on a test stand.
37
Figure 3-15 CO2 emission factors (g/bhp-hr)
The ISX12N MPG on a diesel gallon equivalent (MPGde) basis (assuming 2863gNG/gallon diesel
(14)) ranges from 5.48 MPGde (Cruise) to < 1 MPGde (Creep). For the UDDS test cycle the MPG
was 3.0 MPGde where during previous testing, the ISL G 8.9 L (2010 certified) fuel economy was
found to be ~ 2.3 MPGde on a chassis dynamometer at similar test weights.
38
4 Discussion This section discusses investigation into the real-time data to characterize the impact of the cold
start and transient NOx emissions.
4.1 Transient emissions
Figure 4-1 shows the real-time NOx accumulated mass emission (g) for the three repeated UDDS
cycles (test #1, 2, and 3). All the spikes occur at similar times within the test cycle. Variability
occurs because the magnitude is different, see Figure 4-1. Interesting all the spikes occur during
de-accelerations. This suggests that NOx emissions are essentially zero (estimated at less than <
0.0007 g/bhp-hr) except during sharp de-accelerations. This also suggests > 99% of the hot running
emissions from the ISX12N NZ technology is a result of the transient nature of the truck. It is
interesting that the previous ISL9N NZ transient NOx emissions showed emissions spikes on
accelerations not de-accelerations. It is unclear what changed in the design to cause this.
Figure 4-1 Accumulated NOx emissions (g) hot start UDDS cycles
4.2 Cold start emissions
Cold start emissions represented a significant part of the total emissions as one would expect, but
it is unclear what the real impact from these cold start emissions is on the true regional inventory.
Figure 4-2 shows the accumulated NOx (g) emissions and truck speed as a function of time.
Approximately 90% of the NOx emissions (for all three CS_UDDS tests) occurred in the first 100
seconds of the cold start test. The remaining part of the cold UDDS test was very similar to the hot
UDDS test where emissions spikes occurred at de-accelerations. The UDDS hot/cold weighted
emissions is 0.028 g/bhp-hr (weighted as 1/7th of the hot cycle based on CFR recommendations).
Given that the cold start lasted 50 seconds out of 1080 seconds (total cycle length) the real
weighted cold start emissions in-use for a 4 hr shift will be much less at be represented by 50/14000
or 0.3%. This suggests 0.3% of this vehicles in-use emissions are represented by a cold start as
defined by a 4 hour shift. Also unique to the NG solution, once the catalyst performance is achieved
39
it remains at this high performance unlike the diesel SCR equipped engines where low duty cycle
will cause the NOx emissions to increase again. Catalyst conditions were on average 15C for the
cold start tests and above 300C for the warm starts (20 minute soaks). It is uncertain what the true
warm start emissions will be from regional NG truck usage and will depend on their usage.
Figure 4-2 Accumulated NOx emissions (g) cold start UDDS cycles
40
5 Summary and Conclusions
The testing was performed on UC Riverside’s chassis dynamometer integrated with its mobile
emissions laboratory (MEL) located in Riverside CA just east of the South Coast Air Quality
Management District (SCAQMD). The cycles selected for this study are representative of
operation in the South Coast Air Basin and included the urban dynamometer driving schedule, the
near dock, local, and regional port cycles, and CARB’s heavy duty transient cycles.
One of the difficulties in quantifying NOx emissions at the levels proposed in this research (90%
below the 2010 certification level ~ 0.02 g/bhp-hr) is the dilute measurement methods are close to
the detection limit to quantify NOx emissions at the 5% accuracy expected from the emissions
industry. During previous testing of a NZ engine, UCR upgraded its NOx measurement methods
where it was suggested high ammonia emissions may contribute to the NOx measurement. In this
study it was demonstrated with a spectroscopy method that the low NOx measurements are
accurate even in the presence of high concentrations of NH3. In summary the improved methods
proved to be accurate and reliable where raw sampling was determined to be the most accurate
and precise over the range of conditions tested.
In general the ISX12N 400 met and exceeded the target NOx emissions of 0.02 g/bhp-hr and
maintained those emissions during a range of duty cycles found in the South Coast Air Basin. It is
expected NG vehicles could play a role in the reduction of the south coast high NOx inventory
given the near zero emission factors demonstrated
The main conclusions can be summarized as (conclusions are based on the raw measurement
method):
1. The ISX12N 400 11.9 liter NG engine showed NOx emissions that ranged from 0.012 to
0.006 g/bhp-hr (port cycles) and from 0.001 to 0.02 g/bhp-hr for ARB’s transient truck
cycles.
2. The cold start emissions averaged 0.130 g/bhp-hr for the UDDS test cycle. The UDDS
hot/cold weighted (1/7 cold start weighted) emissions was 0.028 g/bhp-hr which is above
the certified 0.02 g/bhp-hr emission factor. It is expected the impact of the cold start
emissions real in-use emissions could be lower and depend on the real fraction of time a
NG truck operates in cold mode vs hot operation.
3. The NOx emissions did not increase with lower power duty cycles and showed the opposite
trend where the lower power duty cycles showed lower NOx emissions unlike the diesel
counterparts.
4. The real time NOx emissions show consistent NOx spikes resulting during transient de-
accelerations. The cause for variability was the result of the magnitude of the spikes. More
than 90% of the hot running emissions resulted from these NOx spikes. This suggests
possible driver behavior may impact the overall NOx in-use performance of the vehicle and
more gradual de-accelerations are desired for minimum emissions.
5. Total PN averaged from 2e14 #/mi for the ARB Creep cycle and lowest on the Regional
and Cruise cycles (~8e12 #/mi).
6. The solid PN averaged about 50% for all the test cycles.
7. PN is higher (20x) for NG vehicles (8e12 #/mi) compared to diesels equipped with a DPF
(1e11 #/mi). It is unclear what impact this will have locally and regionally.
41
8. NH3 emissions appeared to be lower for the ISX12N compared to the previous testing of
the ISL G NZ 8.9L engine.
9. PM mass was low for the ISX12N truck, but seemed slightly higher than the previous ISL
G NZ 8.9L engine tested.
42
References
1. AQMD 2 October 2015 see: http://www.aqmd.gov/docs/default-
source/Agendas/aqmp/white-paper-working-groups/wp-blueprint-revdf.pdf?sfvrsn=2
2. Wayne Miller, Kent C. Johnson, Thomas Durbin, and Ms. Poornima Dixit 2013, In-Use
Emissions Testing and Demonstration of Retrofit Technology, Final Report Contract
#11612 to SCAQMD December 2013
3. Hesterberg T., Lapin C., Bunn A., Navistar, Inc. 4201 Winfield Road, P.O. Box 1488,
Warrenville, Illinois 60555, VOL. 42, NO. 17, 2008 / ENVIRONMENTAL SCIENCE &
TECHNOLOGY 9 6437
4. Thirubvengadam A., Besch M., Pradhan S., Carder D., and Emission Rates of Regulated
Pollutants from Current Technology Heavy-Duty Diesel and Natural Gas Goods
Movement Vehicles. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2015, 49,
5236−5244
5. Patrick Couch, John Leonard, TIAX Development of a Drayage Truck Chassis
Dynamometer Test Cycle, Port of Long Beach/ Contract HD-7188, 2011.
6. Results from UC Riverside’s Chassis Dyno while testing an 8.9 liter heavy duty vehicle at
transient and state operating modes.
7. Chatterjee, D., Deutschmann, O., and Warnatz, J., Detailed surface reaction mechanism in
a three-way catalyst, Faraday Discussions, 119, pg 371-384 (2001).
8. Cocker III, D. R., Shah, S. D., Johnson, K. C., Zhu, X., Miller, J. W., Norbeck, J. M.,
Development and Application of a Mobile Laboratory for Measuring Emissions from
Diesel Engines. 2. Sampling for Toxics and Particulate Matter, Environ. Sci. Technol. 2004,
38, 6809-6816.
9. Cocker III, D. R, Shah, S. D., Johnson, K. C., Miller, J. W., Norbeck, J. M., Measurement
Allowance Project – On-Road Validation. Final Report to the Measurement Allowance
steering Committee.
10. George Karavalakis, Yu Jiang, Jiacheng Yang, Maryam Hajbabaei, Kent Johnson, Thomas
Durbin, 2016, Gaseous and Particulate Emissions from a Waste Hauler Equipped with a
Stoichiometric Natural Gas Engine on Different Fuel Compositions, SAE Technical Paper
No. 2016-01-0799, Society of Automotive Engineers, World Congress 2016.
11. Hajbabaei, M., Karavalakis, G., Johnson, K.C, Lee, L., and Durbin, T.D., 2013, Impact of
natural gas fuel composition on criteria, toxic, and particle emissions from transit buses
equipped with lean burn and stoichiometric engines, Energy, 62, 425-434.
12. George Karavalakis, Maryam Hajbabaei, Yu Jiang, Jiacheng Yang, Kent C. Johnson,
David R. Cocker; Thomas D. Durbin, 2016, Regulated, Greenhouse Gas, and Particulate
Emissions from Lean-Burn and Stoichiometric Natural Gas Heavy-Duty Vehicles on
Different Fuel Compositions, Fuel, 175, 146-156.
13. Johnson, K., C., Durbin, T., Khan, Y., M., Jung, H., Cocker, D., (2010). Validation Testing
for the PM-PEMS Measurement Allowance Program. California Air Resources Board,
November 2010, Contract No. 07-620
43
14. Johnson, K.C., Durbin, T.D., Cocker, III, D.R., Miller, W.J., Bishnu, D.K., Maldonado, H.,
Moynahan, N., Ensfield, C., Laroo, C.A. (2009) On-road comparison of a portable
emission measurement system with a mobile reference laboratory for a heavy-duty diesel
vehicle, Atmospheric Environment 43 (2009) 2877–2883
15. Cocker III, D. R, Shah, S. D., Johnson, K. C., Miller, J. W., Norbeck, J. M., Development
and Application of a Mobile Laboratory for Measuring Emissions From Diesel Engines I.
Regulated Gaseous Emissions, Environmental Science and Technology. 2004, 38, 2182-
2189.
16. Miller W., Johnson K., C., Durbin T., Dixit P., (2013) In-Use Emissions Testing and
Demonstration of Retrofit Technology for Control of On-Road Heavy-Duty Engines.
17. L&R Committee 2014 Final Report Appendix A ¬– Items: 232-2, 232-3, 237-1, 237-3,
and 237-5: GGE of Natural Gas as Vehicular Fuel.
18. Zhongqing Zheng, Thomas D. Durbin, Jian Xue, Kent C. Johnson, Yang Li, Shaohua
Hu, Tao Huai, Alberto Ayala, David B. Kittelson, and Heejung S. Jung, Comparison of
Particle Mass and Solid Particle Number (SPN) Emissions from a Heavy-Duty Diesel
Vehicle under On-Road Driving Conditions and a Standard Testing Cycle, Environ. Sci.
Technol. 2014, 48, 1779 – 1786.
19. Huai, T., Thomas D. Durbin, Norbeck, J., Analysis of Nitrous Oxide and Ammonia
Emissions from Motor Vehicles. Final report to the California Air Resources Board,
October 2003.
20. Kent C. Johnson., Yu (Jade) Jiang, Jiacheng (Joey) YangUltra, Low NOx Natural Gas
Vehicle Evaluation ISL G NZ, Final report to the South Coast Air Quality Management
District, November 2016.
44
Appendix A. Test Log
This Appendix contains detailed test logs recorded during testing. The testing was performed on Vehicle ID 2018_002, Project Low
NOx 2018, at a test weight of 69,000 lb. The chassis and vehicle operators were Lauren and Don for all the testing and the instrument
operators were Cavan and Lauren. The QCL was operated every day with some startup issues on 1/30/2019 which were fixed and then
selected tests repeated and then issues on 2/5/2018 (during the creep and transient test cycles). Unfortunately the 2/5/2018 issues were
not realized until the data was analyzed. The results were not representative of the exhaust and thus the data were removed from the
report. The creep loads and conditions matches the Near Dock cycle and the Transient conditions match the Local cycle. The N20
emissions were utilized from these cycles for the GHG analysis to estimate impacts from N20 emissions where necessary. Additionally
NH3 emissions were based on UCR’s TDL measurement with the QCL as a backup measurement. The QCL NOx measurements
matched the CLD measurements and the report is based on the CLD measurements.
Table A-1 Summary log for all testing, preparations, and conditioning tests performed in this report.
Date Test Time Vehicle
CE-CERT
Vehicle
Number Project Dyno Cycle MEL Cycle Fuel
Dyno/MEL/ECM_Snapsho
t file Name
Technician/D
river
Weight/
Hp @
50
Vehicle
Weight A B C
1/30/2018 11:57:00 AM 1FUJGBD97FLFY9734 2018_002 CWI-Low Nox UDDS_CS UDDS_CS LNG 201801301146 Mark/Don 107.34 69,500 493.6193 -3.3E-14 0.124575
1/30/2018 12:47:00 PM 1FUJGBD97FLFY9734 2018_002 CWI-Low Nox UDDSx2 UDDSx2 LNG 201801301245 Lauren/Don 107.34 69500 493.6193 -3.3E-14 0.124575
1/30/2018 1:49:00 PM 1FUJGBD97FLFY9734 2018_002 CWI-Low Nox UDDSx2 UDDSx2 LNG 201801301347 Lauren/Don 107.34 69500 493.6193 -3.3E-14 0.124575
1/31/2018 7:15:00 AM 1FUJGBD97FLFY9734 2018_002 CWI-Low Nox UDDS_CS UDDS_CS LNG 201801310712 Lauren/Don 107.34 69500 493.6193 -3.3E-14 0.124575
1/31/2018 8:01:00 AM 1FUJGBD97FLFY9734 2018_002 CWI-Low Nox UDDSx2 UDDSx2 LNG 201801310759 Lauren/Don 107.34 69500 493.6193 -3.3E-14 0.124575
1/31/2018 9:04:00 AM 1FUJGBD97FLFY9734 2018_002 CWI-Low Nox UDDSx2 UDDSx2 LNG 201801310901 Lauren/Don 107.34 69500 493.6193 -3.3E-14 0.124575
1/31/2018 10:41:00 AM 1FUJGBD97FLFY9734 2018_002 CWI-Low Nox DTP1 (Cycle 1) DTP1 LNG 201801311038 Lauren/Don 107.34 69500 493.6193 -3.3E-14 0.124575
1/31/2018 11:59:00 AM 1FUJGBD97FLFY9734 2018_002 CWI-Low Nox DTP2 (Cycle 1) DTP2 LNG 201801311156 Lauren/Don 107.34 69500 493.6193 -3.3E-14 0.124575
1/31/2018 1:25:00 PM 1FUJGBD97FLFY9734 2018_002 CWI-Low Nox DTP3 (Cycle 1) DTP3 LNG 201801311325 Lauren/Don 107.34 69500 493.6193 -3.3E-14 0.124575
2/1/2018 8:21:00 AM 1FUJGBD97FLFY9734 2018_002 CWI-Low Nox DTP 1 (Cycle 2) DTP 1 LNG 201802010818 Lauren/Don 107.34 69500 493.6193 -3.3E-14 0.124575
2/1/2018 9:39:00 AM 1FUJGBD97FLFY9734 2018_002 CWI-Low Nox DTP 1 (Cycle 3) DTP 1 LNG 201802010937 Lauren/Don 107.34 69500 493.6193 -3.3E-14 0.124575
2/1/2018 11:37:00 AM 1FUJGBD97FLFY9734 2018_002 CWI-Low Nox DTP2 (Cycle 2) DTP2 LNG 201802011134 Lauren/Don 107.34 69500 493.6193 -3.3E-14 0.124575
2/1/2018 1:19:00 PM 1FUJGBD97FLFY9734 2018_002 CWI-Low Nox DTP2 (Cycle 3) DTP2 LNG 201802011303 Lauren/Don 107.34 69500 493.6193 -3.3E-14 0.124575
2/2/2018 7:23:00 AM 1FUJGBD97FLFY9735 2018_002 CWI-Low Nox UDDS CS UDDS CS LNG 201802020720 Lauren/Don 107.34 69500 493.6193 -3.3E-14 0.124575
2/2/2018 8:34:00 AM 1FUJGBD97FLFY9735 2018_002 CWI-Low Nox DTP3 (Cycle 2) DTP3 LNG 201802020830 Lauren/Don 107.34 69500 493.6193 -3.3E-14 0.124575
2/2/2018 10:14:00 AM 1FUJGBD97FLFY9735 2018_002 CWI-Low Nox DTP3 (Cycle 3) DTP3 LNG 201802021011 Lauren/Don 107.34 69500 493.6193 -3.3E-14 0.124575
2/2/2018 12:03:00 PM 1FUJGBD97FLFY9735 2018_002 CWI-Low Nox HHDDT Cruise (Cycle 1) HHDDT Cruise LNG 201802021200 Lauren/Don 107.34 69500 493.6193 -3.3E-14 0.124575
2/2/2018 1:07:00 PM 1FUJGBD97FLFY9735 2018_002 CWI-Low Nox HHDDT Cruise (Cycle 2) HHDDT Cruise LNG 201802021305 Lauren/Don 107.34 69500 493.6193 -3.3E-14 0.124575
2/2/2018 2:12:00 PM 1FUJGBD97FLFY9735 2018_002 CWI-Low Nox HHDDT Cruise (Cycle 3) HHDDT Cruise LNG 201802021410 Lauren/Don 107.34 69500 493.6193 -3.3E-14 0.124575
2/5/2018 7:53:00 AM 1FUJGBD97FLFY9735 2018_002 CWI-Low Nox HHDDT Creep x3 (Cycle 1) HHDDT Creep x3 LNG 201802050750 Lauren/Don 107.34 69500 493.6193 -3.3E-14 0.124575
2/5/2018 8:36:00 AM 1FUJGBD97FLFY9735 2018_002 CWI-Low Nox HHDDT Creep x3 (Cycle 2) HHDDT Creep x3 LNG 201802050834 Lauren/Don 107.34 69500 493.6193 -3.3E-14 0.124575
2/5/2018 9:19:00 AM 1FUJGBD97FLFY9735 2018_002 CWI-Low Nox HHDDT Creep x3 (Cycle 3) HHDDT Creep x3 LNG 201802050913 Lauren/Don 107.34 69500 493.6193 -3.3E-14 0.124575
2/5/2018 10:11:00 AM 1FUJGBD97FLFY9735 2018_002 CWI-Low Nox HHDDT Transient_x3 (Cycle 1) HHDDT Transient_x3 LNG 201802051004 Lauren/Don 107.34 69500 493.6193 -3.3E-14 0.124575
2/5/2018 11:13:00 AM 1FUJGBD97FLFY9735 2018_002 CWI-Low Nox HHDDT Transient_x3 (Cycle 2) HHDDT Transient_x3 LNG 201802051108 Lauren/Don 107.34 69500 493.6193 -3.3E-14 0.124575
2/5/2018 12:14:00 PM 1FUJGBD97FLFY9735 2018_002 CWI-Low Nox HHDDT Transient_x3 (Cycle 3) HHDDT Transient_x3 LNG 201802051211 Lauren/Don 107.34 69500 493.6193 -3.3E-14 0.124575
45
Appendix B. Test Cycle Description
The test vehicle utilizes an ISX12N NG engine which is primarily a goods movement engine in
the South Coast Air Basin. As such, UCR tested the vehicle following the three drayage type port
cycles (Near Dock, Local, and Regional), the Urban Dynamometer Driving Schedule (UDDS),
and the HHDDT transient test cycles. These cycles are representative of Sothern California driving
vocations used. Some cycles are very short (less than 30 minutes) where double or triple (2x or 3x)
cycles are recommended in order capture enough PM mass to quantify emissions near 1 mg/bhp-
hr.
Drayage Truck Port (DTP) cycle
TIAX, the Port of Long Beach and the Port of Los Angeles developed the port cycle. Over 1,000
Class 8 drayage trucks at these ports were data logged for trips over a four-week period in 2010.
Five modes were identified based on several driving behaviors: average speed, maximum speed,
energy per mile, distance, and number of stops. These behaviors are associated with different
driving conditions such as queuing or on-dock movement, near-dock, local or regional movement,
and highway movements (see Table B-1 for the phases). The data was compiled and analyzed to
generate a best fit trip (combination of phases). The best-fit trip data was then additionally filtered
(eliminating accelerations over 6 mph/s) to allow operation on a chassis dynamometer.
The final driving schedule is called the drayage port tuck (DPT) cycle and is represented by 3
modes where each mode has three phases to best represent near dock, local, and regional driving
as shown in Table B-1, B-2 and Figure B-1. The near-dock (DTP-1) cycle is composed of phase
1, 2, and 3a from Table B-1. This gives the complete near-dock cycle listed in Table B-2. Similarly,
for the Local and Regional cycles (DPT-2 and DPT-3) the main difference is phase 3, which
changes to 4 and 5 respectively. Phase 1 and 2 remain the same for all three cycles where creep
and low speed transient are considered common for all the port cycles. For this testing it is
recommended to perform phase 1 through 5 individually and to calculate the weighted emissions
from the combined phases for an overall weighing impact.
Table B-1. Drayage Truck Port cycle by phases
Description Phase
#
Distance
mi
Ave Speed
mph
Max Speed
mph
Cycle
length
Creep
1 0.0274 0.295 4.80 335
low speed
transient 2 0.592 2.67 16.8 798
short high speed
transient 3 4.99 9.39 40.6 1913
Long high
speed transient 4 8.09 13.07 46.4 2229
High speed
cruise 5 24.6 35.04 59.3 2528
46
Table B-2. Drayage Truck Port cycle by mode and phases
Description Distance
mi
Ave Speed
mph
Max Speed
Mph Mode 1 Mode 2 Mode 3
Near-dock
PDT1 5.61 6.6 40.6 Creep
Low Speed
Transient
Short High
Speed Transient
Local
PDT2 8.71 9.3 46.4 Creep
Low Speed
Transient
Long High
Speed Transient
Regional
PDT3 27.3 23.2 59.3 Creep
Low Speed
Transient
High Speed
Cruise
Figure B-1 Drayage truck port cycle near dock, local, and regional
0
20
40
60
0 500 1000 1500 2000 2500 3000 3500
Vehic
le S
peed (
mph)
0
1
2
3
4
Phase (
#)
Speed PhaseDTP_1
0
20
40
60
0 1000 2000 3000 4000
Vehic
le S
peed (
mph)
0
1
2
3
4
Phase (
#)
Speed PhaseDTP_2
0
20
40
60
80
0 1000 2000 3000 4000 5000
Vehic
le S
peed (
mph)
0
1
2
3
4
Phase (
#)
Speed PhaseDTP_3
Phase 1
Phase 2
Phase 3
Phase 4
Phase 5
Phase 1
Phase 2
Phase 1
Phase 2
47
Figure B-2 Drayage truck port cycle conditioning segments consisting of phase 3 parts
Urban Dynamometer Driving Schedule (UDDS) description
The Federal heavy-duty vehicle Urban Dynamometer Driving Schedule (UDDS) is a cycle
commonly used to collect emissions data on engines already in heavy, heavy-duty diesel (HHD)
trucks. This cycle covers a distance of 5.55 miles with an average speed of 18.8 mph, sample time
of 1061 seconds, and maximum speed of 58 mph. The speed/time trace for the HUDDS is provided
below in Figures B-3. This cycle was used for all cold start tests as a single test and was performed
in duplicate for all hot tests. Duplicates were used to accumulate sufficient mass for the gravimetric
measurement method.
0
20
40
60
0 500 1000 1500 2000 2500
Vehic
le S
peed (
mph)
DTP_cond1
0
20
40
60
0 500 1000 1500 2000 2500
Vehic
le S
peed (
mph)
DTP_cond2
0
20
40
60
0 500 1000 1500 2000 2500
Vehic
le S
peed (
mph)
DTP_cond3
48
Figure B-3. Speed/Time Trace for a 1xHUDDS cycle.
ARB Cycles HHDDT:
The other three cycles tested were the ARB Creep, Transient, and Cruise cycles
denoted HHDDT_Creep, HHDDT_Transient, and HHDDT_Cruise. The details of
the cycle are summarized in Table B-3 and are presented in Figure B-4, 5, and 6.
The creep and transient were performed as 3x cycles. The cruise was performed as
a 1x cycle. The triple cycle operation was performed in order to obtain sufficient
PM mass on the integrated filter which typically needs around 20 minutes.
Table B-3 Summary of cycle statistics Cycle Total Time
Sec Total Time
(Hour) Average Speed
Distance Max Acceleration
Max Speed
Creep 256 0.071 1.75 0.124 2.30 8.24
Transient 668 0.186 15.4 2.85 2.90 47.5
Cruise 2083 0.579 39.9 23.1 2.14 59.3
0
10
20
30
40
50
60
0 100 200 300 400 500 600 700 800 900 1000 1100
Time (sec)
Sp
eed
(m
ph
)
49
Figure B-4 Speed/Time Trace for a HHDDT_CREEP cycle (performed as 3x) 759 sec
Figure B-5 Speed/Time Trace for a HHDDT_TRANS cycle (performed as 3x) 2004 sec
Figure B-6 Speed/Time Trace for a HHDDT_CRUISE cycle (performed as 1x) 2083 sec
0
2
4
6
8
10
0 50 100 150 200 250 300
Veh
icle
Sp
eed
(m
ph
)
50
Appendix C. UCR Mobile Emission Laboratory
The approach used for measuring the emissions from a vehicle or an engine on a dynamometer is
to connect UCR’s heavy-duty mobile emission lab (MEL) to the total exhaust of the diesel engine.
The details for sampling and measurement methods of mass emission rates from heavy-duty diesel
engines are specified in Code of Federal Regulations (CFR): Protection of the Environment,
Section 40, Part 1065. UCR’s unique heavy-duty diesel mobile emissions laboratory (MEL) is
designed and operated to meet those stringent specifications. MEL is a complex laboratory and a
schematic of the major operating subsystems for MEL are shown in Figure C-1. The accuracy of
MEL’s measurements have been checked/verified against ARB’s 10 and Southwest Research
Institute’s11,12 heavy-duty diesel laboratories. MEL routinely measures Total Hydrocarbons (THC),
Methane, Carbon Monoxide, Carbon Dioxide, Nitrogen Oxides, and Particulate Matter (PM)
emissions from diesel engines. Design capabilities and details of MEL are described in Cocker et
al1, 13 . Samples can be collected for more detailed analyses such as hydrocarbon speciation,
carbonyl emissions, polynuclear aromatic hydrocarbons, etc.
10 Cocker III, D. R., Shah, S. D., Johnson, K. C., Zhu, X., Miller, J. W., Norbeck, J. M., Development and Application
of a Mobile Laboratory for Measuring Emissions from Diesel Engines. 2. Sampling for Toxics and Particulate Matter,
Environ. Sci. Technol. 2004, 38, 6809-6816
11 Cocker III, D. R, Shah, S. D., Johnson, K. C., Miller, J. W., Norbeck, J. M., Measurement Allowance Project – On-
Road Validation. Final Report to the Measurement Allowance steering Committee.
12 Johnson, K.C., Durbin, T.D., Cocker, III, D.R., Miller, W.J., Bishnu, D.K., Maldonado, H., Moynahan, N., Ensfield,
C., Laroo, C.A. (2009) On-road comparison of a portable emission measurement system with a mobile reference
laboratory for a heavy-duty diesel vehicle, Atmospheric Environment 43 (2009) 2877–2883
13 Cocker III, D. R, Shah, S. D., Johnson, K. C., Miller, J. W., Norbeck, J. M., Development and Application of a
Mobile Laboratory for Measuring Emissions From Diesel Engines I. Regulated Gaseous Emissions, Environmental
Science and Technology. 2004, 38, 2182-2189
51
Figure C-1: Major Systems within UCR’s Mobile Emission Lab (MEL)
52
Appendix D. Heavy-Duty Chassis Dynamometer Laboratory
UCR’s chassis dynamometer is an electric AC type design that can simulate inertia loads from
10,000 lb to 80,000 lb which covers a broad range of in-use medium and heavy duty vehicles, see
Figure D-1. The design incorporates 48” rolls, axial loading to prevent tire slippage, 45,000 lb base
inertial plus two large AC drive for achieving a range of inertias. The dyno has the capability to
absorb accelerations and decelerations up to 6 mph/sec and handle wheel loads up to 600 horse
power at 70 mph. This facility was also specially geared to handle slow speed vehicles such as
yard trucks where 200 hp at 15 mph is common.
The chassis dynamometer was designed to accurately perform the new CARB 4 mode cycle, urban
dynamometer driving schedule (UDDS), refuse drive schedule (WHM), bus cycles (CBD), as well
as any speed vs time trace that do not exceed the acceleration and deceleration rates. The load
measurement uses state of the art sensing and is accurate to 0.05% FS and has a response time of
less than 100 ms which is necessary for repeatable and accurate transient testing. The speed
accuracy of the rolls is ± 0.01 mph and has acceleration accuracy of ± 0.02 mph/sec which are both
measured digitally and thus easy to maintain their accuracy. The torque transducer is calibrated as
per CFR 1065 and is a standard method used for determining accurate and reliable wheel loads.
Figure D-1. UCR’s heavy duty chassis eddy current transient dynamometer
53
Mustang Publication “Project Spotlights” March 2010
54
55
Appendix E. Additional Test Data and Results
This appendix includes additional results not presented in the main report. Table E-1 and E-2 are the average and standard deviation
tables for the brake specific emissions for the primary measurements. Table E-3 and E-4 are the emission rates on a g/mi basis. Table
E-5 and E-6 are the particle number emissions in concentration and #/mi. The last two figures in this Appendix are the fuel samples for
the 1st and 2nd fuel test. The QCL was operated every day with some startup issues on 1/30/2019 which were fixed and then selected
tests repeated and then issues on 2/5/2018 (during the creep and transient test cycles). Unfortunately the 2/5/2018 issues were not realized
until the data was analyzed. The results were not representative of the exhaust and thus the data were removed from the report. The
creep loads and conditions matches the Near Dock cycle and the Transient conditions match the Local cycle. The N20 emissions were
utilized from these cycles for the GHG analysis to estimate impacts from N20 emissions where necessary. Additionally NH3 emissions
were based on UCR’s TDL measurement with the QCL as a backup measurement. The QCL NOx measurements matched the CLD
measurements and the report is based on the CLD measurements.
Table E-1 Average emission factors for all cycles (g/bhp-hr)
Table E-2 Standard deviation of the emission factors for all cycles (g/bhp-hr)
Trace Duration Power Work Distance Temp
n/a sec bhp bhp-hr mi C THC CH4 NMHC CO kNOx PM2.5 eBC CO2 TDL_NH3 CLD_NOx QCL_NOx QCL_NO2 QCL_N2O QCL_NH3
CS UDDS 1081 98.97 29.72 5.67 15.48 0.464 0.434 0.030 1.93 0.124 0.0036 0.0004 541 0.051 0.1302 0.157 0.000 0.019 0.183
UDDS 2122 93.40 55.06 11.35 18.80 0.202 0.180 0.022 1.28 0.012 0.0018 0.0007 534 0.112 0.0112 0.013 0.000 0.000 0.123
Near Dock 3049 43.14 36.54 5.81 20.28 0.140 0.181 -0.041 0.74 0.015 0.0015 0.0009 608 0.131 0.0093 0.013 0.002 0.000 0.173
Local 3365 52.90 49.45 8.94 27.82 0.103 0.137 -0.035 0.74 0.015 0.0015 0.0008 611 0.211 0.0064 0.016 0.005 0.000 0.141
Regional 4230 82.24 96.63 27.64 24.89 0.415 0.408 0.007 0.76 0.017 0.0011 0.0007 555 0.146 0.0124 0.016 0.000 0.000 0.122
HHDDT Creep 759 34.69 7.31 0.40 15.83 0.364 0.369 -0.005 0.83 -0.004 0.0040 0.0024 612 0.149 0.0012 - - - 0.149
HHDDT Trans 2004 85.43 47.55 8.91 24.95 0.021 0.018 -0.019 0.23 0.028 0.0013 0.0005 549 0.038 0.0205 - - - 0.038
HHDDT Cruise 2083 107.22 62.04 23.24 29.21 0.343 0.349 -0.007 0.81 0.010 0.0012 0.0008 534 0.062 0.0081 0.011 0.000 0.000 0.084
Dilute Mass Emissions (g/bhp-hr) Raw Mass Emissions (g/bhp-hr)
Trace Duration Power Work Distance Temp
n/a sec bhp bhp-hr mi C THC CH4 NMHC CO kNOx PM2.5 eBC CO2 TDL_NH3 CLD_NOx QCL_NOx QCL_NO2 QCL_N2O QCL_NH3
CS UDDS 0 3.10 0.93 0.02 8.31 0.025 0.026 0.012 0.42 0.022 0.002 0.0001 24.0 0.052 0.0220 0.054 0.000 0.007 0.051
UDDS 0 3.37 1.99 0.05 7.21 0.102 0.066 0.040 0.28 0.002 0.001 0.0002 10.9 0.045 0.0044 0.005 0.000 0.000 0.022
Near Dock 0 1.40 1.18 0.05 4.19 0.060 0.048 0.013 0.07 0.001 0.000 0.0001 26.5 0.077 0.0063 0.009 0.001 0.000 0.007
Local 0 1.13 1.06 0.13 1.32 0.042 0.035 0.008 0.06 0.011 0.000 0.0001 17.4 0.088 0.0030 0.013 0.006 0.000 0.003
Regional 0 1.22 1.44 0.12 5.39 0.018 0.037 0.019 0.23 0.006 0.000 0.0001 21.6 0.082 0.0018 0.009 0.000 0.000 0.014
HHDDT Creep 0 0.64 0.13 0.01 3.03 0.269 0.239 0.030 0.18 0.004 0.002 0.0015 10.5 0.023 0.0006 - - - 0.023
HHDDT Trans 0 1.69 0.94 0.34 1.66 0.009 0.009 0.001 0.08 0.005 0.000 0.0000 6.8 0.025 0.0030 - - - 0.025
HHDDT Cruise 0 3.34 1.93 0.07 0.86 0.084 0.079 0.007 0.14 0.000 0.000 0.0001 11.7 0.070 0.0044 0.006 0.000 0.000 0.016
Dilute Mass Emissions (g/bhp-hr) Raw Mass Emissions (g/bhp-hr)
56
Table E-3 Average emission factors for all cycles (g/mi)
Table E-4 Standard deviation of the emission factors for all cycles (g/mi)
Trace Duration Power Work Distance
n/a sec bhp bhp-hr mi THC CH4 NMHC CO kNOx PM2.5 eBC CO2 TDL_NH3 CLD_NOx QCL_NOx QCL_NO2 QCL_N2O QCL_NH3
CS UDDS 1081 98.97 29.72 5.67 2.428 2.271 0.158 10.11 0.650 0.0193 0.0023 2830 0.273 0.681 0.829 0.000 0.102 0.973
UDDS 2122 93.40 55.06 11.35 0.992 0.881 0.112 6.23 0.060 0.0086 0.0035 2590 0.541 0.054 0.065 0.001 0.000 0.585
Near Dock 3049 43.14 36.54 5.81 0.884 1.140 -0.259 4.63 0.095 0.0096 0.0057 3824 0.836 0.058 0.083 0.014 0.001 1.090
Local 3365 52.90 49.45 8.94 0.572 0.762 -0.193 4.11 0.086 0.0085 0.0045 3382 1.177 0.035 0.091 0.030 0.001 0.779
Regional 4230 82.24 96.63 27.64 1.451 1.428 0.024 2.66 0.061 0.0039 0.0024 1941 0.509 0.043 0.055 0.000 0.002 0.427
HHDDT Creep 759 34.69 7.31 0.40 6.644 6.751 -0.108 15.33 -0.074 0.0743 0.0436 11306 2.739 0.023 - - - 2.739
HHDDT Trans 2004 85.43 47.55 8.91 0.112 0.095 -0.101 1.22 0.149 0.0069 0.0029 2929 0.204 0.109 - - - 0.204
HHDDT Cruise 2083 107.22 62.04 23.24 0.920 0.937 -0.017 2.15 0.027 0.0032 0.0021 1426 0.170 0.022 0.030 0.000 0.001 0.224
Dilute Mass Emissions (g/mi) Raw Mass Emissions (g/mi)
Trace Duration Power Work Distance
n/a sec bhp bhp-hr mi THC CH4 NMHC CO kNOx PM2.5 eBC CO2 TDL_NH3 CLD_NOx QCL_NOx QCL_NO2 QCL_N2O QCL_NH3
CS UDDS 0 3.10 0.93 0.02 0.072 0.072 0.067 2.11 0.104 0.0085 0.0005 48.1 0.284 0.107 0.271 0.001 0.035 0.293
UDDS 0 3.37 1.99 0.05 0.517 0.349 0.195 1.53 0.008 0.0049 0.0010 118.8 0.199 0.021 0.023 0.001 0.000 0.120
Near Dock 0 1.40 1.18 0.05 0.398 0.324 0.077 0.53 0.005 0.0016 0.0007 147.4 0.506 0.038 0.057 0.007 0.001 0.073
Local 0 1.13 1.06 0.13 0.251 0.214 0.038 0.45 0.065 0.0009 0.0004 122.4 0.514 0.017 0.075 0.036 0.001 0.015
Regional 0 1.22 1.44 0.12 0.087 0.150 0.064 0.81 0.022 0.0008 0.0003 41.6 0.282 0.006 0.030 0.000 0.000 0.054
HHDDT Creep 0 0.64 0.13 0.01 4.711 4.178 0.540 2.74 0.077 0.0392 0.0274 220.8 0.346 0.011 - - - 0.346
HHDDT Trans 0 1.69 0.94 0.34 0.051 0.049 0.008 0.43 0.025 0.0011 0.0002 77.5 0.131 0.018 - - - 0.131
HHDDT Cruise 0 3.34 1.93 0.07 0.254 0.241 0.018 0.38 0.002 0.0004 0.0004 14.3 0.196 0.013 0.018 0.000 0.001 0.050
Dilute Mass Emissions (g/mi) Raw Mass Emissions (g/mi)
57
Table E-3 Average emissions particle number results and others (#/mi, #/cc and concentration)
Table E-4 Standard deviation for particle number results and others (#/mi, #/cc and concentration)
Trace Power Distance Vmix
n/a bhp mi m3 CPC CPC_CS EEPS Total_PN Solid_PN EEPS % Solid TDL QCL
CS_UDDS 99.0 5.67 1519.0 111717 49262 78577 3.0E+13 1.3E+13 1.1E+13 44% 16.08 40.95
UDDS 93.4 11.35 2981.5 43119 31799 29310 1.1E+13 8.0E+12 72% 41.92 41.09
DPT1 43.1 5.81 4285.5 39206 27668 27054 2.9E+13 2.0E+13 1.3E+13 71% 40.07 54.80
DPT2 52.9 8.94 4730.6 36499 20154 33268 1.9E+13 1.1E+13 7.9E+12 55% 62.01 43.39
DPT3 82.2 27.64 5943.6 40502 20585 26985 8.7E+12 4.4E+12 3.9E+12 52% 47.62 42.44
HHDDT_Creep 34.7 0.40 1066.1 81629 25421 46625 2.2E+14 6.8E+13 1.3E+14 31% 45.69 45.69
HHDDT_Trans 85.4 8.91 2814.4 57794 25512 38421 1.8E+13 8.1E+12 1.2E+13 44% 10.15 20.15
HHDDT_Cruise 107.2 23.24 2927.8 60022 22074 41724 7.6E+12 2.8E+12 5.3E+12 37% 21.54 23.58
#/cc #/mi NH3_ppm
Trace Power Distance Vmix
n/a bhp mi m3 CPC CPC_CS EEPS Total_PN Solid_PN EEPS % Solid TDL QCL
CS_UDDS 3.1 0.02 0.6 29525 14821 29525 7.8E+12 3.9E+12 1.5E+13 2% 15.85 6.09
UDDS 3.4 0.05 1.3 10101 2851 10101 2.7E+12 4.8E+11 13% 16.22 6.01
DPT1 1.4 0.05 2.0 5467 4401 2703 4.2E+12 3.3E+12 1.2E+13 7% 27.27 2.03
DPT2 1.1 0.13 0.9 2840 989 5260 1.3E+12 6.6E+11 1.1E+13 7% 28.48 3.26
DPT3 1.2 0.12 2.4 9089 2671 897 1.9E+12 5.6E+11 3.4E+12 5% 20.49 3.18
HHDDT_Creep 0.6 0.01 0.1 14052 8994 11189 3.4E+13 2.3E+13 3.1E+13 6% 6.30 3.15
HHDDT_Trans 1.7 0.34 0.4 3749 2339 1857 1.6E+12 1.1E+12 5.3E+11 5% 11.73 5.33
HHDDT_Cruise 3.3 0.07 0.3 7900 3077 2500 1.0E+12 4.0E+11 3.2E+11 2% 26.14 5.07
#/cc #/mi NH3_ppm
58
Fuel Sample #1
59
Fuel Sample #2
60
Appendix F. Engine certification family, details, and ratings
This appendix includes the engine executive order Figure F-1 as listed on the ARB website for the
family number tested JCEXH0729XBC with engine rating ISX 12N 400. • For model year 2018,
the 8.9 liter engine is called the “L9N”. Prior to 2018, the engine name was “ISL G” for the 0.2g
NOx version and “ISL G Near Zero” for the 0.02g NOx version
Figure F-1 Engine certification order for the ISX 12N NG engine (ARB source)
Figure F-2 Test engine label
61
Appendix G. Coastdown methods
Road load coefficients are important where at 65 mph the aerodynamic term accounts for 53% of
the resisting force, rolling resistance 32%, driveline losses 6% and auxiliary loads at 9%. These
load fractions vary with speed and the square of the speed where a properly configured
dynamometer is needed to simulate the loads from 0 to 70 mph. The method for determining
coastdown coefficients was published and evaluated as part of a study submitted to the South Coast
Air Quality Management District14. Typical coastdown procedures assume that vehicle loading
force is a function of vehicle speed, drag coefficient, frontal area and tire rolling resistance
coefficient and takes the form of equation 1:
𝑀𝑑𝑉
𝑑𝑡=
1
2𝜌𝐴𝐶𝐷𝑉2 + 𝜇𝑀𝑔𝑐𝑜𝑠(𝜃) + 𝑀𝑔𝑠𝑖𝑛(𝜃) (Equation 1)
Where:
M = mass of vehicle in lb (tractor + payload + trailer+ 125lb/tire)
ρ = density of air in kg/m3.
A = frontal area of vehicle in square feet, see Figure G-1 below
CD = aerodynamic drag coefficient (unit less).
V = speed vehicle is traveling in mph.
μ = tire rolling resistance coefficient (unit less).
ɡ = acceleration due to gravity = 32.1740 ft/sec2.
θ = angle of inclination of the road grade in degrees (this becomes zero).
Assuming that the vehicle loading is characteristic of this equation, speed-time data collected
during the coastdown test can be used with static measurements (ZET/NZET mass, air density,
frontal area, and grade) to solve for drag coefficient (Cd) and tire rolling resistance coefficient (µ).
The frontal area is measured based on the method described in Figure G-1 below. However,
experience performing in-use coastdowns is complex and requires grades of less than 0.5% over
miles of distance, average wind speeds < 10 mph ± 2.3 mph gusts and < 5 mph cross wind15. As
such, performing in-use coastdowns in CA where grade and wind are unpredictable are unreliable
where a calculated approach is more consistent and appropriate. Additionally vehicles equipped
with automatic transmissions have shown that on-road loading is also affected by the
characteristics of the vehicle transmission, especially when reverse pumping losses at low speed
begin to dominate.
UCR’s and others recommend a road load determination method that uses a characteristic
coastdown equation, with a measured vehicle frontal area (per SAE J1263 measurement
recommendations), a tire rolling resistance μ, and a coefficient of drag (Cd) as listed in Table G-
1. If low rolling resistant tires are used then the fuel savings can be employed with a slightly
improved coefficient as listed. Similarly if an aerodynamic tractor design is utilized (ie a certified
SmartWay design) then a lower drag coefficient can be selected. Table G-1 lists the coefficients
14 Draft Test Plan Re: SCAQMD RFP#P2011-6, “In-Use Emissions Testing and Demonstration of Retrofit Technology for
Control of On-Road Heavy-Duty Engines”, October 2011 15 EPA Final rulemaking to establish greenhouse gas emissions standards and fuel efficiency standards for medium and heavy duty
engines and vehicles, Office of Transportation and Air Quality, August 2011 (Page 3-7) and J1263 coast down procedure for fuel
economy measurements
62
to use based on different ZET/NZET configurations. Once the coefficients are selected then they
can be used in the above equation to calculate coastdown times to be used for calculating the A,
B, C coefficients in Equation 2 for the dynamometer operation parameters. From these equations
calculate the coastdown times from based on the coefficients in Table G-1 as shown in Table G-2
(65,000 lb, ustd, Cdstd and Table G-1). From Table G-2 one can plot the force (lb) vs average
speed bin to get the ABC coefficients for the chassis dynamometer (see Figure G-2). These are the
coefficients to enter into the chassis dynamometer then validate via the details of Appendix C.
Repeat process until validation criteria is met. Typically one or two iterations is needed to meet
the validation criteria.
Table G-1 Constants and parameters for Class 8 heavy duty trucks
Variable Value Description
θ 0 no grade in these tests
ρ 1.202 standard air density kg/m3
μstd 0.00710 standard tires
μadv 0.00696 low rolling resistant tires
CD_std 0.750 for non-SmartWay tractor
CD_adv 0.712 for SmartWay tractor
ɡ 9.806 nominal value m/sec2
M Varies mass: final test weight kg 1 The tire rolling resistance, μ, for low rolling resistant tires shows a 1-2% savings (ref SmartWay). As such utilize
0.00686 fpr low rolling resistant tires. In this document the tractors may vary, but the trailers will be assumed similar.
As such, if the tractor utilizes the certified SmartWay tractor type then coefficient of drag can be reduced by up to
10% (5% fuel savings) depending on the technology. As such in this guidance document utilize the Cd_adv for
SmartWay tractors and Cd_std for non-SmartWay tractors. Additionally, for reference other vocations show higher
Cd’s, such as the CD = 0.79 for buses and 0.80 for refuse trucks. Nominal value of gravity is used in this document
where actual value can be found by following 40CFR 1065.630 or at http://www.ngs.noaa.gov
𝑑𝑉
𝑑𝑡=
1
2
𝜌𝐴𝐶𝐷𝑉2
𝑀+ 𝜇𝑔𝑐𝑜𝑠(𝜃) + 𝑔𝑠𝑖𝑛(𝜃) (Equation 2)
63
Figure G-1 Vehicle frontal area dimensions method
Using Equation 2 (solution for 𝑑𝑉
𝑑𝑡 or deceleration), one can calculate the deceleration for each
average speed bin (60, 50, … down to 20 mph), see Table G-2. From the deceleration time one
can calculate the desired time which is the target for the coast down simulation on the chassis
dynamometer. Using the final test weight (M), the total simulated force can be calculated using
Equation 1 at each speed bin, see values Table G-2. Plot the simulated force (lb) on the y-axis vs
truck speed (mph) on the x-axis. Using a best fit polynomial of order two, calculate the polynomial
coefficients A (0th order term), B (1st order term), and C (2nd order term), see Figure G-2. Enter
these ABCs into your chassis dynamometer and verify the coast down times match your desired
coast down times to within 5%.
The calculation approach is consistent and has proven very reliable for chassis testing heavy duty
vehicle and has been used for years by UCR and others. For detailed evaluation of aerodynamic
modifications and body styles, UCR recommends investing the time perform in-use coastdowns
where sufficient program resources will be needed as per 40 CFR Part 1066, SAE J2263, and
J1263.
Table G-2 Desired coastdown times for a Class 8 truck with standard components
Avg Speed Calc Time Decel Decel Decel Force
Data Point MPH sec MPH/Sec ft/sec2
Gs lb
65-55 60 25.67 0.38954 0.57 0.018 1154
55-45 50 31.44 0.31806 0.47 0.014 942
45-35 40 38.51 0.25965 0.38 0.012 769
35-25 30 46.68 0.21422 0.31 0.010 635
25-15 20 55.02 0.18177 0.27 0.008 539
Desired
64
Figure G-2 Resulting ABCs based on Table G-2 results